SE/30 won't format floppies

[PacificState]

I have an SE30 that I'm resurrecting, but it won't format floppy disks successfully - the format goes through, but verification fails more or less immediately. However, I have another SE/30 MLB - and if I swap it in, the floppy formats fine every time.

I've replaced RP10 with no change - am I now right in suspecting the SWIM chip? Thanks!

 

[Jamieson]

I pulled the floppy drive on my SE/30 cleaned the heads and lubricated the moving metal bits. Reads floppies OK. When I try to format or write to a floppy it either fails or locks up the machine. Any suggestions where to look? I just recapped the logic board and cleaned it really well in IPA.

 

[bcschmidt]

Did you happen to lift up on the upper head when you were cleaning it? Very easy to stretch that spring? Weird that it locks up though.

 

[Jamieson]

Yes, very gently lifted up on that. Just enough to get a swap in there to clean it. It looks like it seats ok with a disk installed. Is the upper head used for writing and the lower for reading?

 

[Berenod]

Might be a long shot, but is the original shielding of the floppy drive present?
I've heard of failing formatting due to the effect of electromagnetic pollution coming from the powersupply / analog board/ crt when the metal shields are not (properly) in place!