So I got bone stock Mac 128k which was suffering from the apparent common problem of the screen not turning on, but slapping the right side of the case causes it to jitter on for a moment. I reflowed the solder on that connector as most guides I've found instruct. However, that did not solve the problem. With the case open and power on, I carefully wiggled the J1 yoke connector cable and it started working. So I think the problem is with the wiring harness/connector itself. Has anyone seen or repaired this? I'd prefer not to have to solder the wires directly to the analog board if a better option exists?