I've tried using a cleaning disk (not one with the alcohol fluid, but a dry one that doesn't spin) but that did not work.
Strange thing is: both diskdrives do the same, shouldn't I look somewhere else for the drive error?
I have one that doesn't read disks, but what I didn't realise is that it actually corrupts track 0 of every disk you put in and try to boot off it. Not sure if that is paula/cia or something else.