Hi,

> It is not the tapes, since I can read install tapes much of the
> time.  The scsi TK50's usually read about 50% of the time.  The
> tmscp TK50's are now reading only about 25% of the time or less.
> I am using many different tapes.  I am not able to write tapes
> hardly at all on any of them.
> 
> I am wondering if it might be a track alignment and if I can
> fully erase (bulk erase maybe?) the tapes somehow for a fresh
> run.  I don't see any driver driven way to erase the TK50 tapes?
> mt, both in Ultrix and NetBSD has no erase capability.   I tried
> writing zeros and ones and then random, but that did not help
> much.  I sense I really need a clean erase on these old tapes.
> 

I never thought about an erase option.  I have always done the
dd if=/dev/zero of=/dev/rst8 bs=1m stuff.

> What, in particular in the mechanism needs to be looked at for
> cleaning other than the head (idiot lights maybe?)?
> 
> What, in particular wears out in the mechanisms?

I was told by a dealer in used DEC stuff that the heads are made
out of a very soft alloy and as a result wears out very quickly 
because of the abrasive nature of the tapes.

I am not saying this IS the problem, but I myself went through two
TK-50 drives a few years ago and in every case it was a worn out
head.  I even practically doused the drive in Isopropyl Alcohol and
it didn't help anything :-)

Andy