A500 - Problem reading non-dos disks

I have one of my A500s which almost never reads non-dos disks. Even Workbench/Dos disks sometimes have difficulty reading.

It also does not always know if a disk is inserted or not but that is not really the issue and if the disk is inserted properly it attempts to read.

I basically had rescued this A500 and it was really really dirty, not only dust but even leaves, insects and all sorts of rubbish. The RF shield was all rusted out and the top cover of the disk drive is being eaten away by corrosion.

Surprisingly the case, after a really good clean up has no yellowing whatsoever and looks fantastic.

Anyway, i have a replacement drive which i know works fine, but when I hooked it up it gave me exactly the same problem except it always knows when a disk is inserted.

My point, is there something wrong with the actual Amiga ? The board is a Rev5 with Kickstart 1.2.

Sack & re-insert CIA chips, plus Paula. If no enhancement, check for dry joints on the solder points in the floppy data header (on the motherboard, of course).

About the iffy floppy detection, nothing a drop of anti-rust oil in the detection switch (one of the two near the unit window) will not cure.