In that case, please make more tests after re-capping the original PSU. We did have negative reports with Gotek drives ever since the ACA500 came out in 2013, and I never had the chance to investigate that. If you have some electronics knowledge, it may be worth a try to insert an inductor into the supply line of the Gotek drive, so pulsing power consumption does not fire back into the host system. That's just a shot in the dark, but the best "educated guess" I can provide.
Please also understand that official product support ends here - you have successfully shown that our products work fine with the A500. Only if an extra component by a third vendor is added, you have trouble. I'd like to hear what the vendor of the Gotek drive has to say, especially about power consumption and power filtering.