Problem tape

[bty997881]

I am but a single tape away from returning my first batch of 'The 400', but this last tape is 
proving to be a right bastard.
 Although there's no visible damage, the tape will not play all the way through, despite 
having been re-housed three times, numerous rewinds, and having tried it in three different 
machines - a Denon, a Tascam and a Marantz. The Marantz actually managed to get all the 
way through one side, but cannot play the other.
It's very odd, because there is no damage that you can see, but somehow the tape becomes 
very reluctant to move in the middle section and eventually grinds to a halt. It doesn't appear 
to be contaminated in any way ( I once had a box of tapes that got covered in olive oil after 
an emergency stop in a VW camper, and boy were they difficult to play ;-) ), and the spools 
appear to be evenly wound.

 So should I give up on this one (tape 080 , 21.5.79, btw) and return them to Rocker, or does 
anyone have any suggestions? 
cheers
Roger