Fairlight-CMI

Hi everyone, 

I have just got hold of 30 used Tapes, but as I'm browsing them 
(DIRTAPE command), my CMI says they're either blank (even though 
there are supposed to be files on them) or I get the 
message "Unexpected Tape Error 3". These are all compatible 3M 
DC600A Tapes and most of them are dated around 1988-1989. 

I have a couple of other tapes (Memorex MRX600A) which read and 
write fine, so does this mean the 30 3M tapes are buggered or is 
there a possibility my streamer could be faulty? By faulty, I mean 
in need of a clean (no idea when this was last done), in need of re-
allignment (is this possible?) or anything else anyone can suggest.

I know this is an extension of my previous posts, but these tapes 
have quite a cool history and I'm VERY eager to get my hands on 
their contents...

Thanks in advance! 

Kind Regards, 
Peter