fixing reel-to-reels?

["diatom drone" <skincage@infin8ty.com>]

My dad got a new stereo so he's given me permission to go into vulture mode
and pick over the remains of his old system (which for the most part has
been moved between houses but barely used) to use as possible studio
components. As this system is older than I am, his amp has tubes (glee) but
the output is a bit scrapy until the volume is cranked to a certain level.
Thanks to past posts, I'm aware that it might just be a worn out pot, and
thus might be able to fix that easily.

The main issue though is his old Sony tape deck (TC-336 is the model). The
controls seem to be in order, the LEDs work etc. The only thing that seems
amiss is that reels won't move when the directional control is engaged.
Could this be a belt issue? I've taken apart a few cassette players for
parts but I've never worked on a reel-to-reel. I definitely don't want to
screw it up, but there's not anywhere around here that could likely fix it.
It seems to be a really nice deck, and I'd hate for it to just get 
scrapped,
especially with the possibility of using it as part of a mastering chain.

As always any and all insight is much appreciated!

Jon