How about just bypassing the whole oscillator while retaining processor control and monitoring? Disconnect the emitter of Q12, the anode of CR22 and the right end of R48. Put in a voltage divider made of 2 10k resistors between the node previously connected to Q12's emitter and 5V with the divider output connected to J1-8. I'd draw the modification but I can't download the schematic. You might have to change the divider ratio to get above 0.2V at J1-8 for all drive modes (3 processor outputs at J1-15, 17, 18).
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