First post so here goes, I did search best I could before posting.

First pin to own is this Buck Rogers in amazing cosmetic and mostly mechanical shape. Things I've already done:
*Ground Boards to back plane
*Replaced "the big capacitor" on PS.
*Added LED to PS, MPU +5 -12, add LED to Driver for +5 indication.
*checked for +5 and -12 at MPU, adjusted 5v pot it was at 6v.
*replaced Kicker Transistor TIPS-102 and burned up coil.
*replaced 5 bank drop target coil (#8) and MPS-45 and 2N3055, replaced MPS with a CEN-45 from Mouser.
*All LED (frosted) on playfield and back glass.
*Confirmed proper fuses and function.

Once I did all above things worked fine. Played about 40 games then bam, 5 bank drop target won't reset. It gives about a 1/2 effort like it would come up then stop. I tested by grounding the 2N3055 and the target would pop up. PS felt pretty warm on the heat sink. Let it cool and worked about 4 games then same thing. Found the CEN-U45 was out, replaced and worked fine for about 10 games. BAM out again.

So my question is this, what do I need to look for? is this a voltage issue? I'm stumped. Getting tired of replacing this transistor too!

Fun game family loves it.

Components sourced from Mouser. 2N3055G shows ON Semiconductor. U45 reading with + on center pin and - on right shows OPEN where new shows I believe .7. So it's blowing that transistor however the 2N3055 shows good still. I checked the 1/2w and 1/4 watt resistors on each side tested OK. 900 ohm and I believe the 1/4 w were 1k ohm. All wiring and pins original. I did burnish the board pads with a fiber brush. Traces look ok under a magnifying glass. Will pull and take to work tomorrow and double check it all. Perhaps the 2N3055 is low in gain?

When I removed Q45 the board was very dark and showed signs of high heat it's possible I suppose that there was some damage to trace but not seeing anything obvious.

You may have nailed it. I double checked. R39 is a 9ohm +/- 5% 1/2 w resistor but it testes 12.1 ohm. Well out of spec. R37-38 are 1k and with in spec. So maybe the higher resistance is whacking it out of range. I hate not having parts on hand. I'll order it.

IMG_2272 (resized).jpg

Resistor did not fix the issue. Same as before it will reset a few times then it only pushes the drops 1/2 way up and back down.

GRRR at a loss.