yep I get that too - mostly on clean, super fast shots up there where the ball hits the wall to make the final downward turn toward the wheel, but actually bounces back through the gate. i've always chalked that one up as 'one of those pinball things' and never bothered to tweak

I'm fairly certain (someone feel free to fact check me) that Williams moved the diodes off of the coils and onto the backbox driver board starting with System 11B (i.e. Big Guns and onward). In the process caused an unforeseen symptom that LED flashers tied to coils 3, 4, 6 and 7 to light up when flippers are flipped.

you can - there is a procedure that I've used on 4 of my system 11B machines. For transparency I did not author the steps below, but I'm having trouble finding the genius to give credit to. All I can say is that it works:

1. Purchase 1N400x diodes on Amzn. The "x" can be any number. I used 1N4001 but the others work too. You can get 50 of these for $3 shipped. Good to have on hand.

2. Find the aux power board in the backbox. It's located near the middle of the right side, BELOW the power supply (power supply has large heatsink). Find the diodes labeled D3, D4, D6, and D7 (diode = small wire with the black thing in the middle) on the aux power board. They are all next to each other vertically. Use a wire cutter to completely remove those four diodes I just mentioned.

3. Now find coils 3, 4, 6, and 7 under your playfield. If you have no clue which those are, grab the manual for your game and find the solenoid table, usually found towards the beginning. In the table, you will see the Solenoid # (i.e. the coil #) and then the function describes what it is so you can identify it. In Dr. Dude, you want the Ray coil, Gab coil, drop target coil, and knocker coil (you can skip that one if you disconnected it).

4. Solder a 1N400x diode to each of the above coils, with the gray banded side of the diode attaching to the power wire lug (power wire is the thicker wire of the two attached) and the non-banded side attaching to the other lug

****************
For Cyclone:
Coil 3 = skill shot kicker
Coil 4 = boomerang kicker
Coil 6 = (not used)
Coil 7 = Knocker

flame polishing works, but with the risk of warping the plastic all to hell if you're not careful. i've done it myself, so if I can do it, for real anyone can.

The flasher under that insert will light up on the coil 1 C-Side test (along with the backbox Jackpot flasher). The description of the test reads:
L.FERRIS JACKPOT
05 01 'C' SIDE