Recently I bought a new turntable, TTUSB Numark, and I just started to notice that there are some pitch changes when I play records. I believe that this was initially not the case.
At first I thought that it might be the vinyl record itself, but after trying different vinyls I noticed that the problem is not record specific. Moreover, the random pitch change on a certain record is not specific to a certain place/time in the record. I can't re-produce the problem so to say at, for example, time 1:33 of record X. Also, it is not a continuous problem, but seems to happen approximately 2 a 3 times per side, and I can hear the pitch change for something between 2-8 seconds.
Does anybody have an idea what could cause this, and if yes, how to fix it?