I cleaned my drop targets on my Flash as they would not reset once all knocked down. as you can find on the forums, the drop downs are all connected in series so once all knocked down, they complete the circuit to tell the electronics to fire the solenoid. The horseshoe contacts are pretty sensitive and a couple had to be readjusted after I cleaned them and then they worked.. However, once I put them all back together, I blew up the TIP for the center 3 targets (lots of smoke and the transistor package was blown apart!). Turned out I didn't solder the solenoid wire back to the solenoid - <duh> and the wire shorted to the bracket, so after replacing the TIP, the same thing happened again.... <ugh!> turns out I reversed the wires on the solenoid, so the diode would always conduct and I basically had shorted the 35V though the TIP... Long story short, if your coils are burned or the TIPs are getting blown, make sure the wires are not reversed on the solenoid. I haven't seen a diode failed shorted, but that could also be the case.
It's a great game once it gets working!