The displays in my Lost World work great for ~10 mins, then they start bugging out. Hit the forums to try to figure it out, and found this thread (https://pinside.com/pinball/forum/topic/odd-problem-bally-star-trek) which is quite close to my problem. During test, the player displays display all 0s, then all 2s, then all 4s, etc., BUT the credit display acts completely differently. It only displays odds... Sometimes the displays will flicker between two different digits (let's say it's supposed to be displaying all 7s, sometimes it will flicker between the 6s which are improperly being displayed, and 7s which are supposed to be displayed- this behavior happens to all the displays, and is independent of the other displays). These issues persist no matter the amount of displays plugged in.
190v and 5v are solid, power supply has been rebuilt.
Repinned all MPU connectors.
Checking the output pins from MPU chip U10 (PA0-PA7) to their respective J1 pins shows 1.2kohms for all.
One of the displays is a -15 revision which doesn't have the 20k resistors leading from the header pins to the chip. Would this make a difference at all?
On the rest of the displays which are the -21 revision, chip U1 pin 5 to J1 pin 19 gives ~20kohms for all.
Pulled U10 and cleaned the legs, reseated.
Video of the problems: https://drive.google.com/file/d/1tAlhzbtR9_6THxnGlqAAMXVradW3mQo3/view?usp=sharing
I'm leaning toward a bad U10 and/or a bad 40-pin socket? Any help appreciated