Lee182jib

Hi A couple of weeks ago I bought a Project Primary and everything was great for the first week but lately there has been a kind of high pitch hum that starts about 5 min into any record I play. After a bit of switching things around I found that the hum was coming from the turntable and not the speakers, and there was no noise when the belt was removed from the plinth, so it seems to me (in my very limited experience) that the noise is caused by some kind of friction going on when the plinth is spinning. Has anyone experienced this or have any suggestions on how to fix this? Thanks Edit: I think I may have gotten plinth and platter mixed up. When the belt is fitted and the platter is spinning there is noise, if i take the belt off so the platter doesn't spin there is no noise. So I think the noise is caused where the platter fits into the plinth.