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Now it starts to get interesting...

Before I say anything here, I want to say Thank You to Russ Jensen for writing his book on early pinball electrical systems,
"Russ Jensen's Pinball Troubleshooting Guide". Without it, I would have been even more clueless about any of this.

        I decided to do the electrical work first to see if I had to find any parts.

        After vacuuming out the cabinet and backglass areas, I traced out all of
    the nonoriginal wiring I found, so I could see what I needed to repair. The         left switch at the top of the photo was for power, and the one on the right         was for turning on the added payout latching solenoid at the bottom left of         the photo. I removed all of this when I repaired the cabinet wiring. The
    brass tilt bob and rod was missing too, so I have to replace it.

Airway Backboard Wiring

        At left is the photo of the backboard wiring as I
    found it. Installed halfway up the right side of the
    backboard was two relays mounted on a bent piece
    of steel. I traced out the wiring, and the input of these
    relays was wired so they turned on whenever the
    player won 1800 points. When these turned on, they
    sent power down to the payout locking solenoid at
    the bottom of the top photo. When the payout solenoid
    turned on, the payout mechanism unlocked and the
    machine paid out a nickel at the beginning of the
    next game. I decided to leave these alone for now
    so I could study how they worked.

Fuseholder

        When I installed a new power cord, I found this broken         fuseholder clip in the left photo so I replaced it with a new
    fuseholder and a 5 amp 110 volt fuse. I was 'on a roll', so
    I decided to plug it in and see what would happen. I
    powered up the Airway, and got nothing. I turned off the
    power, traced the wiring from the fuse, and found the
    playfield's power switch was under the round steel timer
    bell at the bottom left of the photo on the right. I cleaned
    and oiled the timer and switch, reassembled the machine,
    and turned on the power switch, still nothing. Then I
    remembered... When I worked on my wife's 1951 Bally
    Spot Lite bingo, I had no end of problems with the 'pin and hole' cable terminations shown in the
    middle of the left photo. The cable end pins were just pressed together, so when they got
    tarnished and dirty, the pin connections all stopped conducting electricity and nothing worked.
    Since the terminals in this Airway were exactly the same as the ones in my wife's Spot Lite, I cleaned and soldered all
    of the pins on all of the cable plugs together, cleaned all the sockets with a chemical deoxidizer, reconnected all the
    plugs, and turned on the power. The tilt relay in the upper left of the backboard started clicking on and off, and my son
    Adam ran in from the other room shouting... 'Dad, the lights are on!'.

        So, now I have to fix the tilt.... Since the tilt bob
    and rod is missing, the only tilt switch left is the
    slam switch in the bottom of the machine in the
    photo at the top of this page. I cleaned and
    adjusted this switch, and then moved to this bank
    of relays pictured at right. The top relay is the tilt
    relay, the middle relay is the main power relay,
    and the bottom relay is the stepper relay, which
    moves the scoring rotary switch. The switch
    between the top and middle coils is the main
    power switch. When you push in the coin chute,
    the playfield power switch turns on, turning on the
    main power relay. This pulls down the main power
    switch, sending power to the rest of the machine.

     When the machine is tilted, the tilt relay turns on,
     pulling up the main power switch, turning off the
    power to everything except the round white TILT area in the cloud next to the MILES column on the right side of the
    backglass. I cleaned the main power switch and stepping relay, took apart and cleaned the tilt solenoid, but the tilt
    relay still chatters when it turns on. Oh well... I'll get it later when I find the tilt bob.

        When the Airway first came on, the scoring lights were stuck on at the highest
    scoring position, so I still had problems with the scoring.

       The photo at left shows the scoring stepping switch mechanism stuck at the
    highest scoring position. The lower photo at left shows the solenoid coils and
    ratchet - the red one at left moves the ratchet to the next position when the next
    score registers, winding up the coil spring under the movable rotary contact in
    the top photo.

        In this photo, the black solenoid at the right unlatches the ratchet mechanism
    for a new game, unwinding the coil spring and resetting the score to zero. I
    cleaned the mechanism with compressed air, cleaned and oiled all the ratchet
    pivot points and the mainshaft until the mechanism advanced and reset properly
    by hand, cleaned and checked the leaf switches, and used a plain steel wire
    brush in my Dremel tool to clean the switching contacts on the bakelite disc.
    Once all of the terminals were cleaned, the scoring lights all worked properly
    when I stepped the switch by hand.

        The Airway used Bally's earliest lighted 'spring'
    bumpers, patented in 1936. This bumper was made
    of a large coil spring, a brass ring inset into the
    playfield, a S-shaped mounting bracket, a light bulb
    the same color as the associated airplane, a light
    bulb socket, a colored bumper cap, and some
    screws. The brass ring had a carbon ring inside it,
    and each brass ring was soldered to the center
    (insulated wire) conductor of the light bulb socket
    inside the bumper. The bumper was fed 48 volts AC through the S-shaped mounting bracket and the coil spring. When
    the ball hit the bumper pictured at left, it moved the spring extension inside the brass ring inset into the playfield. If the
    bumper moved far enough, the spring extension hit the ring and 'closed the contact', turned on the 18 volt light bulb
    inside the bumper, Bumper Relay Bank

and turned on one of the relays in this cabinet bank pictured at left. Each bumper had its own
    solenoid, and each relay in this bank was set up as a latching
   (locked 'on' once energized until reset) switch. As each of these
   relays fired, it sent power to the lowest solenoid mounted under
   the TILT and main power relays in the backbox, which advanced
   the stepping switch and advanced the scoring lights. Also, the
   colored light bulb under the bumper spring and the associated
   plane painted on the backglass lit up at the same time.

       Anyway, more issues...

       The #5, #7 and #10 bumpers wouldn't do anything when you
   moved them. The #1 was working well, and the others either didn't
   fire their solenoids, flashed their bulbs dimly when I activated them
   or not flashed at all. So, I checked out #1 bumper, and I found out
   that there was four very important things to check. If your solder
    joints between the center connection of the light bulb and the brass ring were bad then nothing would work, if the
    connection between the S-shaped bracket and its bare wire was bad then the bumper was 'weak', if any of the
    underplayfield metal parts were touching any of the others the stepping switch relay would be stuck on loudly, and
    if the light bulb socket shell was dirty or the shell's solder connection to it was bad then the bumper lights wouldn't
    come on. So I cleaned all the S-shaped brackets and their wire connections one by one, wire brushed out all of the
    light bulb sockets, and resoldered all of the solder connections to each bumper. Then, I cleaned and checked each of
    the cabinet bank's relays, and now all of the bumpers work. Now, if I could only find colored light bulbs the right size
    for under the bumpers...

These are the last three playfield switches. These all are activated when you move the coin slide, which moves the shutter under the playfield.