Tape looks fine but won't play?

I can't play back a tape that I own that is part of a trilogy. The other two tapes play fine and the three tapes all look the same except for a scuff mark/scratch on the clear plastic portion on the front of the tape in question. Is there anything I can do to get it to play back properly? As it stands, the picture is there but it's constantly moving up and down with black static lines going along it.

Amy
March 2009