Understand and research DE/Sega Version 3 board sets based on manufactured games of the 1991-1994 period. The DE CPU 3 board is a non-reflexive board is much different than previous versions on several coil driving transistors for switchable coils. This is beyond standard TRex motor assembly and it's PCB control board which is one of the game's Achilles heels. More than the side to side action, other components break in the jaw. Too many amateur repairs and bad operator hacks at this point since 1993. All other standard game "watch outs" apply, such as outgassing displays, plastics, ramps, scoops, and kick out saucers. The kick out Trex saucer is generally equally chewed from scoops. Other areas including the motor brush wear out and the shaker motor fuse board which gets colder solder joints due to vibration. The gun handle assembly is hard to find and the I don't know if the "smart missile" button has been reproduced. People sometimes used this handle as a "lift assembly" and unlike BLY/WMS gun handles, it just immediately can get cracked.
I can list a lot more, but that was a baseline.
PM if you have more questions or require a game assessment.
This is includes the other title, JM, that I have owned since 1996.
That is a great game, with a handful of completely different problems, but usually beyond the glove and X/Y nuts, and motor, including cracked ramps due to speed shots and missing components such as signage, Crazy Bob and the Phone Matrix board which classifies as plastics. The cabinets are generally nuclear blasts of yellow versus red.