HI everyone,

I'm trying to repair a disk drive for the Commodore 1541-II (for Commodore 64), and I’ve run into a strange issue.

From what I can see (based on diagnostics/screenshots), the head reads between tracks quite well, but does not align with the actual tracks.

The behavior is consistent across all tracks (from track 1 to 35):

- I cannot read any whole-number tracks
- I can read all half-tracks (e.g., 18.5 reads reasonably well)
- Track 18 shows as “needs adjustment”, while 18.5 is readable

It really looks like the head is shifted by half a step.

Electronics (main board) are definitely OK — I tested it in another known-good drive.

So this seems to be a mechanical issue. However:

* I aligned track 0 using a diagnostic tool, and it reports “perfect”
* I tried adjusting by slightly loosening the stepper motor screws — almost no effect
* The best I could achieve was changing the message from “NEAR HALF TRACK” to “HALF TRACK”

But I simply cannot shift the head enough for it to properly read full tracks.

At this point I’m stuck. Has anyone seen similar behavior or has ideas what else I could try?

Thanks in advance.