Usually on the 68xx "Inspired" drivers, when the galvo slams to one side after a major power supply fault, replace the LM7915 voltage regulator. Check for +/- 15V on the board before reconnecting the galvo. It is not wise to run the amp for long periods of time without a known good galvo connected, but 20-30 seconds to make a voltage measurement should not blow the output stage. Don't trust the LEDs, make an actual measurement.
Steve
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...