If the problem stays in the same location with a different display, the slaves are ok. Could be a harness/connector issue.
If the MDB is also showing the same problem, could be outgassing of the MDB and it's bringing down the slaves. You can try reseating the connectors on the MPU (top three 9 pin connectors on the MPU board). If that's doesn't help and it passes the self test, it's the glass.
viperrwk