Newbie issues/questions on my 1969 Gottlieb Airport Game

In both a 1 and 2 player game, sometimes the play and score reels are incorrect. Either it skips to Player 2 in a 1 player game, or in a 2 Player game, it goes from Player 1, to Player 2 and then immediately skips back to Player 1 without allowing Player 2 to utilize the playfield.

Where in the machine is the 2nd Player activated and what does it change in the machine?

The match process seems to work at the end, and I get a thump in the back box, but there are no lights and the credit wheel does not move.

Generic question on the Stepper units in the back box? There seem to be more rivets on the Ball Count stepper than balls(it's labeled Ball Count 0-9). Does a complete game cause a 360 degree rotation on the stepper unit, or a complete rotation of the stepper unit involve multiple games? What do each of the sensors/pickups on the rivets do?

Two steppers in the Back Box, 1 labeled Ball Count Unit and 0-9 Unit. How do these stepper units work and how do they control play?

Thanks. Will order some reference guides tomorrow.

Thanks. So the order in the sequential ball count is Player 1 Ball 1, followed by Player 2 Ball 1, followed by Player 1 Ball 2 and so on.

In a single player game, what controls skipping over the “Player 2 Rivets”?

Yes thanks. What would cause random problems? I will try and clean any of the contacts.