The reason I'm suspecting alignment is that the 1541s are notorious for going out over time, especially after a long hard run - which is exactly what my working one had directly before it developed this new not-reading issue
To test my hypothesis I pulled the Newtronics mech from another 1541 I have which has a power supply problem and swapped it into the drive which had been working. Briefly, it could read/write correctly too - but it soon failed a load sequence then refused to load again.
Might be time to get down and dirty with the DMM though, just in case... otherwise, it'll be time to break out the alignment tools.
Just the local Commodore hobo and middle-aged PC hoarder.
eisa on Trademe. A lasting reminder of a Compaq fetish when I was younger.