Nothing is unfixable and Corvette is a very fun game so don't let minor annoyances stop you. If it's cosmetics thats another story but technical problems, bah. We'll get ya going with that, not to worry

There are several boards that control the ZR5 movements. The first board is a
small controller board in the backbox. It has two ribbon cables going to it (one from the CPU board, and another going to the ZR5 board under the playfield.) this backbox ZR5 control board rarely has problems.The problematic board is the ZR5 board mounted under the playfield, directly below the ZR5 playfield toy. This board has two LM324 chips, an analog to digital converter chips, and four TIP102 transistors. The transistors have huge heat sinks. And it’s not uncommon for one of these TIP102 transistor to short, and then bake the board.

Yeah. I don't mess with the boards on games that don't boot. I figure I can send them away for repair. I definitely use that as a bargaining chip. I do check to make sure they are repairable though.

The engine controller board is a common issue. It also has 4 coils and one may be bad.
The raceway uses belts and a gearbox which may have broken. You can see the belts thru the slots. You can buy these at Marcos. It also has a controller board and two opto boards.
I have been lucky so far and have had no issues with my engine or track.

Make sure that large right ramp is not cracked. I have not seen a replacement, and since it is so freakin huge, it will cost a bucket if you do.

I'm having the same problem, did you ever figure out what the cause was?