Very true. I apologise for my short, undetailed response before. I was using my phone which was not cooperating. But, I think you and I are on the same page anyway.
What it sounds like is happening is: The head positions to track 18, writes the directory, reads it back, determines it's not correct, and repositions the head and tries again. You should be able to verify this by watching the head position with the drive apart whilst it is formatting. The only reason to do this is this: If the alignment really is off far enough, it's very remotely possible for track 18 to format correctly, but track 1 to fail.
Also, when the drive activity light is flashing, the command channel contains an error message. In '128 mode, you can type ?DS;DS$ to read the error number and message. However, it's important in this case to get the track and sector of the error, which cannot be done so simply. If you do this the old fashioned way, you can get that information. You'll have to write a short program to do it:
1 OPEN15,8,15
2 INPUT#15,A,B$,C,D
3 PRINTA;B$C;D
4 CLOSE15
You will probably see
21 READ ERROR 18 0
The 18 and 0 are track 18 and sector 0. This confirms that the drive is unable to format the first sector of the directory track, which rules out severe misalignment. It doesn't totally rule out incorrect hub speed, but I'd suspect a read/write error first.
If you get an error number besides 21, please let us know. There are several different read errors you can get, but I don't recall how to determine what each one means. It may be possible to determine that something was written and actually read back, but scrambled. That could mean a speed error rather than a lack of read/write. If the disk is spinning too slowly, the beginning of the track will be over-written with the end of it, maybe. That assumes the whole track is written at once, and I'm not sure that it is. I used to know all about the interleave and how the drive works, but I seem to have forgotten most of that!
