
Does it do it to all tapes?  Were the two tapes that it unwound of the same
type from the same batch?  The reason I ask is that I bought some generic tapes
that did this and found that the tape markers were not fully punched out and
had closed the little marker hole.  It was only on a few tapes of a set.

Did you open up the tape cartridge and put the tape back on the reels?

If you have not yet, open it up by removing the two screws on the bottom of
the tape cartridge and snap the plastic shell away from the metal base.  
As you are pulling the tape through the assembly try not to touch any more 
than you have to.  As you are doing it, look for a couple of little holes in 
the tape.  These are the marker holes which let the tape drive know when it is 
at the end of the tape.  The holes are spaced a couple of inches apart.  My best
guess is that the drive finds the first marker and then stops on the second
marker?  

Anyhow, If the tape has the holes, then check to see if the mirror on the tape
is clean.  The function of the mirror is to detect the marker holes.  The
tape drive shines a light at the mirror and has a pickup in the area where
the reflection would come out.  When the hole goes by, the pickup detects the 
light that was allowed to pass and it knows when to stop.  If the mirror is dirty
or out of alighment (unlikely since it is made into the case) you might have
a problem detecting the end of the tape.

If the tape drive does it on all tapes and the tapes all look good, then either
the pickup or the LED of the sensor system has failed or is dirty.  If you open
the drive door you will see the sensor assembly to the left of the R/W head
assembly.  If it looks clean and nothing is in its way, then the drive may
need to be serviced.  It is possible that the LED is burned out or the sensor
is out. 

If it is still in warranty, you might be able to send it back to CMS for
repair.


---
Scott Hiles
whiles@relay.nswc.navy.mil