Ok, I'll probably get scolded here as I actually have similar issues on two separate machines (and yes, different manufactures) so I may need to split these up to get the correct answers, but the issues are so similar, hoping possibly same fix?

Machines -
1976 Bally Hang Glider
1976 Williams Space Mission

For some reason, both play great in single player mode. But when I hit the credit button again for multi-player, they both add players - buttt:

Hang Glider - Plays Ball # 1 for each player, but then sticks on Ball # 1 for player # 4 - never advancing after that.

Space Mission - Once I hit the credit button for more players, it stays on Ball # 1, Player # 1..never advancing after that.

Are these similar issues, or different fixes?

Is it the ball count unit, or the player unit? Thinking just a cleaning on the contacts?

Any & all help is appreciated, thanks !

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On both machines -they’re pretty gummed up or something as they don’t move freely -as in coin eject

I do notice - again I think on both - even though they’re both set up to free play, when I deposit a coin , it automatically starts a game (like I hit the start button)

Sorry. I thought you meant the coin mechanisms in the door. Lol. My bad. Though that was causing some issues ugh

Now that ive looked at the links. I see what you’re talking about. I’ll check on that and report back on this one. Thanks !

Cleaning the coin unit and the player unit seemed to have fixed the Williams Space Mission. A big thank you!

Still have some long delays when the ball goes into a bonus hole (any of the 4). Just gives more points than it should more times than not.

Did the same to the Bally Hang Glider - but still same results as before. “Coin” up (hit start twice) for 2 players and it goes thru all 4 players and stays on ball 1 on the 4th player.

Ok - cleaned both again this morning. (The fingers and the brass/copper plate side). Amazing amount of crud built up.
Also cleaned the SCR 3b.
The coin unit is in the cab
The player unit is in the head
Games works perfect on one player. Set at 5 balls. All works well

Still getting 4 players when I only hit the start button twice and then on the fourth player - it sticks on ball one never advancing

I’ll review the links above to check if I can find anything. (Needle in a haystack. Lol)

At least it’s getting some much needed cleaning !

Rolf has saved me before!!!

Ok, tired to check before work -

so - if I hit the start button once, for one player, the game goes through all 5 balls as it should, no issues.

If I hit the start button for 2, 3 or 4 players - in each instance, it automatically goes to 4 players, and keeps on ball one for player four, never advancing.

I've cleaned (thoroughly) - the coin unit, the player up unit, even the bonus unit. I've checked, cleaned the jones plugs (although I do not know which one is directly related to tis issue).

Note: This game is set to "free play" (I don't know how it was set up for this) - so just wondering, could how they have this set up for free play be messing with the player count issues I'm seeing?

I'll look at those jones plugs and the score motor switch shown above, this is great help, thank you again!

Aha! Mark this one as solved! Had time to pull the playfield out enough to check those last two relays. One of which is the Player Reset relay. Be it stuck or dirty but once cleaned up -I’m getting correct operation. All number of players All number of balls.

“Chas10e” - you helped me fix two games quickly there - and more importantly I know where to look on the next Similar issue (and perhaps another noobie can do a search and find this helpful) so thanks a lot for the help!