SE/30 floppy format error

[ScutBoy]

I have an SE/30 that I recapped that appears to be working correctly except for one thing. It will read floppies correctly, and will write floppies some of the time, but the rest of the time, and _always_ when I try to format a floppy, it will crash with a "bus error" in the Finder, or just lock up solid.

This is under System 7.5.3. I wiped the disk and re-installed the system software, but the problem persisted. I swapped in a known good 1.4 floppy drive, and the problem persisted. Different logic board in the same chassis/analog board worked OK.

I've gone back over my work after the recap and don't find anything obvious like corroded chip legs or lingering cap crud - though I certainly could have missed something.

Any ideas on what/where to check next appreciated!

 

[ScutBoy]

Update - with more testing, it seems to be consistent with an Error 10 in the Finder.

I realize Error 10 can be many,many things...

 

[MacOfAllTrades]

This is unlikely to align with your problem - but on my SE/30 I had/have similar issues.
I noticed if, after inserting the floppy, I used my finger+nail to give the seated floppy when final extra push forward into the machine that it would now be able to format with much more likelihood. I ended up cleaning up the floppy drive (even more) and lubricating it (even more) and this must have let it get a little further in during injection than before and it helped. Very weird, I know and I never got to the bottom of it really, just colloquial junk :-/.
But pushing it in with your finger is an easy 'test' to run.