Nintendo 64 game is flaky

[CanadianAtari2]

Hey guys, I recently bought a copy of Mario cart 64. I was told it was not working but after using some isopropyl alcohol 99 percent on the pins and re-flowing all the solder points it maybe worked every 10 attempts and has now stopped entirely. The games board looks very very clean. Anyone have any ideas? Another weird part is I took all the shields off and the black cover for the pins and it worked sometimes and not others. Now it just seems to not work at all.