As a last resort I take the boards out of the case and put them in the mobo out of case..Making sure to put them in the mobo exactly like they'd go in as if they were still in the caee.
This way I couls have 1 board up slightly higher then the other incase it's not making contact at certain spots..
With the game in case don't piush it all the way into the mobo.or rather push it all the way in and they pull it up slightly to have it make contact at a different spot of the connectors..
If after all my intense cleaning,checking for cart wobble,no warping in the case.sliding nicely into the mobo
plus clearing the back up ram memory..then the carts got a problem that I can't fix
If a cart won't slide smoothly into the mobo,I know it's going to have a problem..
With the link port games(two holes in case for link ports),I had a game shoved into a case (YATON)that didn't have holes for the ports,........because of that one of the boards was being pressed forward....The two cart edges didn't meet perfectly so one was going firther into the mobo then the other...I had to cut holes in the case to have the link ports stick out of it...
I have a Thrash Rally MVS Cart..Not sure really what they go for now..