Well, the C128 showed up today with everything I needed to diagnose my issues with the 1541 and...

.. it was the drive. Replacing the machine and the cable made no difference. Swap in the 1571 and everything works great.

Bummer. But I do have a working machine now!

Thanks for giving me hope that I hadn't missed something obvious. My C128 and 1571 should be showing up soon.

Of course I could always pull out my multitester...

I just got my 1541 delivered today and given that I have a C64 and all the cables, I figured I'd see if I couldn't get a disk working. Well, after hooking everything up per the manual and getting both a power light and a short red light and some noise after inserting a disk, I tuned on the C64 and ...