I love my Special Force. Dollar for dollar it is the most fun game in the lineup.
Sadly, these 6803 are riddled with problems and the electronics are crap.
I was having several issues with mine that I could not resolve. Luckily, NOS boards for these pins are plentiful and inexpensive. I ended up paying $80 for a brand new driver/MPU board from a local op that had a big stash of them and I never had issues again.
I know this doesn't help your current situation, but something to think about.