Stan,

>   IIRC, the controllers for the TK-50 and TK-70 are different. Another
> glitch may be trying to use a TK-50 tape instead of a TK-70. Apparently,
> the timing track is written the first time a new (blank0 tape is written
> to, and the timing tracks are different between the TK-50 and the TK-70.
> Comments have been made about media differences, although I've
> demagentized a TK-50 tape (with $1.00's worth of magnets!) and written
> to it in a TK-70 drive. This is "officially" frowned upon, and I'm not
> counting on that tape for a backup....YMMV.....

Could you describe the demagnetization process more thoroughly?  I've got 
quite a few TK50 tapes right now, but only a handful of TK70's.  The 
latter are hard to come buy.  One that I picked up still had a price 
tag on it: $29.95, marked down from $49.95!  I didn't pay that much,
I'm happy to say.

Doug