Problem 1 sounds like the problem my Bally wizard had which turned out to be the coin unit. So whatever controls the number of players on a Williams. One of more of the fingers were not making contact in player 1, but 2-4 player worked normally. Yours sounds like the reverse.

Well, it could be a few things. I had a similar issue with mine. It was the score motor in my case (may not be the same in yours). I found a set of leaf switches on the 2 impulse cams were broke and out of adjustment.

Your problem looks a bit different though as mine just kept going on the correct number of players but never talking to the ball count unit. Maybe start by observing and possibly taking video of the 3 steppers, the two on the bottom board which I believe are the coin and ball count units as well as the player unit in the back box. If we start there while you start a game and cycle through, perhaps we can see what is going on and it will lead us down the path to diagnosis through the schematic.

Good luck!

Check the m&b for fault.

Wms Strato.JPG

Ever check the player unit?
Here are some snips of the schematic and from the manual showing the score motor switches for both step up of the ball count unit & player unit step up.
P.u. -S.u..JPG
Manual P.u. disc.JPG

The player unit is located in the backbox and has essentially four positions.
The coin unit determines/controls the amount of players by each advance of its step up coin coil which effects the player unit.
The manual for the player unit disc shows the wiper @ reset in the Player one position and when additional players are added via the coin unit it that will effect the player unit which will advance to the next player only after the ball for that player has played.
S.u. desc..JPG
B.c.u.d..JPG

*Note the player unit disc only moves 3 steps forward max. with only 4 positions possible remember.
For example: when you have a 4 player game set each player drains the ball after the index locks then the player unit bumps up one step till the 4th pl. drains after which the Player unit resets back to the player one position w/2nd ball ready to play.

Sounds to me like you have an issue with the player unit disc,as it should return to the first player position no matter how many players are selected ,a clean and lube of the rivet contacts/pivot points and possibly an increase in that torsion spring to return it fully,but you only increase tension if a C&L fails to correct it as the manual suggests.

To speed up diagnostics set up a 4 player game then you should be able to manually advance it to the 4th player and upon draining the ball [after the index locks in] watch the reset coil activate and return to the player one.
Good Luck.

I am encountering exactly the same problem with the Triple Bonus relay tripping. Most often after a reset. Was just about to dig into it when I came across this thread.
Can you let me know exactly what it was? Weak latch? Thanks.

Thanks! I'll dig into it!