My RFM used to do the same thing from time to time - green bleeding across the screen. Mine would do it from time to time, then got a bit worse, but still intermittent.
I managed to trace the fault back to a bad connection on one of the two connectors goinginto the PC - try reseating things at that end and see how you go.
IIRC the connector that was causing my fault wasn't actually the one that feeds the monitor, but the larger one that does everything else.
HTH
Definitely will check that one just in case, And use some CO cleaner that I uses for electricals at work to clean ports and wires
I'd really like to know where to buy new ribbon cables and new cga port for the rfm pc, I've looked in jaycar but no go... old technology is getting scarce
