I actually had about the same problem...with my F-14. Went 'round and 'round with the usual stuff, replacing diodes etc... still had the mysterious random tilts. I finally found that the upper "T" target was causing the tilts. Did the usual diode replacement again on that target. Still tilts.

I took the target switch out and ohm'd it for continuity and proper operation and it appeared to work fine out of the game. Reinstalled it and guess what - still tilted! I ordered a new switch and replaced it, and the problem was gone for good. I never knew what exactly within the switch was causing it, but I suspect that perhaps the rivet through the "sandwich" of the switch base was probably shorting somehow, I just never saw it with a meter.

I assume that your Fire right flipper has a lane change switch off of the cabinet switch. Try replacing the switch along with the diode, unless I am wrong about Fire and your matrix switch triggered by the right flipper is off of the right flipper EOS.

I agree - it was bizarre for sure...and maybe as you said. I did think about tearing the switch apart - for a moment - but figured that in itself might disturb whatever was wrong with the switch construction, and it's around 25 years old. I had fought the problem for so long I was just glad to be done with it.

That's really bizzare. The purpose of the diodes, as most know, is to prevent damage to the coil driving circuity from back spikes of voltage created when the coil is shutoff and the magnetic field collapses. This is totally unrelated to the switch matrix and really none of those circuits overlap, unless there was induced noise from the coil circuit playfield wires running close to the switch matrix wires - that's all I can possibly think of, besides some outright coincidence. Wouldn't be the first time something strange happened with a pin.