You do seem to be in good hands. You guys will get it.

Hi Nikrox2
thanks for post-100. Through the full schematics, hmm - see the JPG: There is a Jones-Plug in the pin - with wire-58-5-White-Black in it / on it. Unsolder away this wire / the wire from the socket. Then try the pin - does the pin functions (of course but not the 500 points plus bonus) ?
ipdb does not have the manual to Hokus Pokus - I looked up on "Flip Flop" https://www.ipdb.org/files/889/Bally_1976_Flip_Flop_Manual.pdf - on page-3 two Adj-Plugs for 3-5 ball adjustment are shown, so I allowed myself to redraw the JPG on the wiring (maybe true maybe false).
Anyway when Your pin have no longer the fault when wire-58-5-White-Black is unsoldered - You must follow this wire up to the playfield --- follow where-ever it goes - not only look at "gaps on switches" wide open --- also look for "stud of a blade with wire soldered-on", stud bent making faulty contact (?) - or a drop of solder fallen there ?, or a doghair crap of wire ? See here http://www.pinrepair.com/em/index2.htm#fuses - scroll down to the third picture - see a bent stud (well the stud on a lamp is bent - but also could happen with a stud on a switch). You may also look here http://www.pinrepair.com/em/index2.htm#scorereelsvideo - scroll upwards two pictures - Star-Rollover-Switches on a Captn. Fantastic ... Greetings Rolf

0Hokus-Pokus-Work-05 (resized).jpg

So what was the problem