i have a bally embryon that wont boot. it just gets the first flicker when powered on. having recently got this machine, it has booted a few times (with no sound) but now wont boot anymore. i found on the back of the mpu were jumper wires to different stuff. i reflowed those wires and it booted a couple of times. i thought it was fixed but then stopped booting again. i read up on jumpers to investigate closer, and found the wires on the back of MPU are not the jumpers but are mostly going from U2 to different stuff. Im confused as to what they are there for at all. And also inspecting each jumper, i found only about half of them were correct. but it had booted previously.
why would these jumpers from U2 and other places be necessary? some wires connect to U1 and U3, where there arent even chips.
anyone seen this or did this before?
thanks

IMG_20180118_153127198 (resized).jpg

IMG_20180118_153115533 (resized).jpg

heres a pic with labels for clarity

embryon (resized).jpg

well that worked. there were a few that were open that i reflowed. it just booted up.

any thoughts as to if i should replace U2 socket and correct jumpers, or just leave be?

thanks for the help
-barry