Hi Barky
You approach Your problem assuming "wrong soldering". Maybe it is - maybe not. Merf is guiding - I would like to get answer from You (because I do not completely understand).
In post-1 you write "1P Reels won't reset to 0" - "Two of the reels at the same time".
Question: You start a game - do 1P Reels do step some steps ? Do ALL 1P Reels do some steps ? How far do they step ? If You manually set the 1P reels to 23450 - what happens at start of a new game ?
To me it is common: On Reset-Cycle Reels step "together" (they are pulsed by the same relay).
Does the Reset-Cycle end in some (crummy) way (what ?) - can You play the given (?) ball ? - and NOW (making points) it happens: "Two of the reels step at the same time" ? Greetings Rolf