Unfortunately it didn't want to accept the
cleaning
 tape (just spat it
 straight back out again) - I was worried there was a
 fault with the tape
 transport, but it's accepted one of the 8mm
 cartridges just fine. 
Check to be sure the cleaning tape isn't all the way
at the end. Those cleaning tapes are good for maybe
10-20 cleans - the drive won't rewind them (not like a
DLT cleaning tape, that has to be rewound). Once it
gets to the end, it insists on not using it. You can
manually rewind them, although you're really not
supposed to - might cause more harm than good, putting
junk back on the heads. Best not to clean the drive
unless it needs it.
-Ian