I have an FDS that works fine somedays, and spews out all of those error codes on other days, I assume due to fluctuations in temperature and humidity. Same game, different results from day to day. Proper tuning seems to be critical for proper operation.

It's not for the faint of heart, but there is a guide available here:

http://www.famicomdisksystem.com/tut...nt-adjustment/

I have no personal experience aligning FDS drives (yet), but this guide seems to be very comprehensive.