Hello, I work as a tech in a retail store repairing gaming machines of all kinds. I was employed at Bally, Aristocrat, GLI, AGS, Colossal Gaming as well as a couple of start-up companies in Las Vegas. I've been around and have seen many interesting issues with gaming machines but can usually solve them eventually. This time, I might be beat though.

I have an iGame with originally a WBA 12 (ID-24) that renders the game to display "Bill Validator Comm Failure - Options Verification Required"
So the first thing I tried was to use another working WBA from a different IGT machine in the store just to test to see if it clears up. I've tried a combination of WBA 11-13 all ID24. Same issue. I then figured that I'd try to use an MEI Cashflow (the older yellow ones) which seem to be much more reliable than JCM WBA. Made sure it was ID24... same result.
The second thing I tried was to test the main board in a different iGame and it worked just fine. The BV worked.
The third thing I tried was to replace the backplane board (behind the main board). I tried 6 boards. Same issue.
The fourth and final thing that I tried was to tone out the harness from the connector on the backplane board all the way to the BV connectors where they plug into the actual BV. That all tested OK.
I haven't used a hammer (yet) but admittedly "did" take one spare BV and smashed it on the ground. That felt great (no worries, it was a parts/junk BV).
Wait... yes I did RAM clear it several times in between tests. Just in case that would do anything but of course I wasn't so lucky.
Does anyone here know what possibly can be causing this? I don't have much experience with IGT but have noticed that this brand is somewhat "delicate" and fussy.
Please advise.
Thanks!
Mod Note: Topic split and edited