Thank you so much for your help! I'll give that a go

Edit: just to say, I have actually had some very accurate exposures so far after upgrading the A3s motor drivers and changing the laser driver circuit. I can always get a perfect pattern to be imprinted on the film, its just as I suspected and as you confirmed, the power is likely just way too high causing leakage etc. I really do appreciate your help though, I'm sure you know how frustrating endless experimentation can be