anything electronic is hit n miss at the best of times..hence the reason, all manufacturers of pinballs in the past, and even stern give 3 months max on all computer boards etc etc...so if the manufacturer himself only gives a short cycle, it is fair to say something 20 yrs old is unreliable at best...
when ever i buy a pin, i always understand that something or even everything could go wrong...just part of the hobby....like marriage really..lol.
i bought a bugs bunny pin recently on ebay $1610...after i won it, the owner told me the machine was not working and felt it "was a transistor or something"....he said he would take off a hundred and fifty bux..i said fine...it took my good mate andrew (beaky) 30 minutes and $10 stuff from jaycar to fix...part of the hobby, ya win some , you half lose others...
hey, at least the owner did mention the thing wasnt working, eventually...and the bid was only on $600 at lunch today...i think u have a good point, but the guys who bid after the listing was changed, knew it was still a great deal...but u did make a valid point...maybe his listing was slack versus intentional .who knows..
buying pins is fun, fixing them, not so much....maybe....