The belt should be correct if it's from Tascam.
Maybe it's experiencing a stretch of it's own, anyway. Belts of a certain age would tend to stretch as they warm up. YMMV.
I'd disagree w/GFM, that the 244 is capable of 'stellar' results on par with the latest Portastudios, and are not limited by their mic preamps, which sound quite good. That it's a 1/4" input does not automatically make it an inferior preamp. I would never say the 244 sounds inferior to the likes of the 424mkIII, however they do sound slightly different. They're of different designs, eras and components, kinda like varieties of apples, a very close comparison. Heh, heh.
The 244 would have to be aligned & calibrated for the comparison to be valid, though many 244's out there have not been calibrated since being set factory.
I wish I had more time to tinker on gear, due to how much inoperative & fixit gear I've acquired, but sometimes you might want to skip the techy stuff and just record. On balance, if you desire to work with vintage gear, some gear maintenance is necessary and it worth it [imo], though it may be a real pain, plain & simple.