Pitch problem. Help

Hi folks,

I've had my Goldring GR1.2 for a few months now. Wonderful entry level table. Sometimes it sounds so good it's downright spooky. Quiet, accurate, and lush.

Other times, I can hear fairly serious pitch inaccuracies - especially on guitar or piano, I can literally here the pitch wobbling up and down.

This seems to change day-to-day. Last night, I listened to my new Johnny Cash album and was stunned. This afternoon, the pitch wobble has reared its ugly head, and the magic is gone.

What's happening here? Why would this happen some times and not others, on the same record? And what can I do?

Many thanks for your help.
also check to see that the motor pulley is secure to its shaft.If it's loose, a tiny drop of superglue will do the trick.
these days power sucks- Add a speed controller and get a strobe and a strobe disc to check rpm there are several such as VPI SDS also other inexpensive ones check Music direct or a-gon etc. I have the SDS which puts the magic back regardless of input current.
I've recently ordered a Clearaudio synchro to address this problem but you might want to also check into the other various speed controllers which are available, such as the Project Speed Box or Speed Box SE;
"This tiny black box allows painless speed change between 33 and 45 rpm with the mere push of a button. But that's not all. This neat little box offers quartz-generated electronic speed regulation. In other words, the Speed Box isolates the attached turntable from line voltage fluctuations that can affect speed stability. The quartz oscillator boasts a speed stability of +/- .01%. The more upscale Speed Box SE offers speed stability ten times better than the Speed Box. If you think a fraction of a percent of speed variation wouldn't have much of an audible affect, you should hear what the diminutive Speed Box can do. I'll get to it later but it literally blew me away. I truly did not expect the degree of sonic mprovements that this little CDN$129 box delivered."
6moons Speed Box review
From what I just read, the Speed Box seems to be an AC synchronous device. It will not work with all turntables and it won't work with turntables that have DC motors. It won't work with certain Project turntables. I would check with the manufacturer to see if it will work with your particular turntable before ordering one...
It's a belt-drive, right? Check to see that the belt is correctly centered on the pulley and the platter, and that it isn't defective (torn or stretched).

If the belt is fine, power may indeed be the culprit.