I have a 20mb Sider hard drive that was working fine then when I turned it on it sped up way past the normal RPM. Of course also not working. Tried without the interface card with the same results. Tried with a different power supply as well. Now I’m wondering if the drives circuit board controls the speed or is that a function of the drive motor. My reason is that a long time back I got a few dead Siders from a former Apple II mail order seller. I believe there’s a couple of identical dead drives there.