Most of this was posted on rgp ages ago...but bought my first Firepower in 2000, non-working, in an operator's storage unit bulk deal (along with an inop Time Warp and a bunch of classic vids & parts) - decent playfield and cabinet, typical crackled backglass. Spent some time getting it working, bought an "NOS" backglass for it that turned out to be a repro (the original ones with the thinner glass and wrong color/opacity inks that had hot spots from the GI lighting). Really fell in love with the game though. Spent the next few years upgrading/switching pieces around as I'd owned several more examples of the title, including one I bought at auction that looked like it had been in a fire, literally.
Around 2004 I picked up the best original example of one I'd ever seen, and still own it. Great cabinet (although it's got a few very minor touch-ups), very nice playfield, and even a great original backglass.
It's an early production game with some hints of "prototype" features; it has the cutouts behind the middle standup target banks for the extra leaf switch that would have been utilized if the game had shipped with drop targets (prototype design), dimples in the underside for drop target mech mounting screws as well. The extra leaf switches are wired. Had the target bank plastics without the blue border at the leading edge, which was added later when the design was changed to standup targets; I took those off and set them aside for regular plastics with the blue edge as they cover the targets better.
Got tired of the constant hassles with the ball trough so I converted it to microswitches. No more trough problems! If I recall, I used a spare trough plate from a T2, and some other misc. spare parts. Also converted the flippers to modern WPC style baseplate/bushing/coil stop design.
After rolling the score over a few too many times I decided it was time to do the 7 digit conversion. Installed a level 7 MPU, display controller board, and displays - and burned a set of Oliver Kaegi's excellent custom game ROMs, giving the game 7 digit scoring and the multiball award/skill shot enhancements.