SDS question


Hello friends,
I was checking my turntable speed today using my KAB speed strobe and found that my table was running quite slow. I had the VPI SDS calibrated at 59.85hz and I thought I had the speed perfect. Today, I needed to adjust it to 60.03hz to get it dead accurate again.
What might cause such a big change to have to be made? I was wondering if it might be the weather (it has turned cold recently here in Chicago)?
Any thoughts would be appreciated.
Thanks.
tfkaudio
Just following up on Starcons' comments, I was at 60.54 before hooking up my PS Audio PPP. Now the SDS is at 60.00 and my turntable sound is noticeably improved.
OK...I forgot belt slipage. I am a DD guy where the speed of the platter is the same as the motor, and the motor is exact. I really don't think that there should be any belt slipage...you probably need a new belt.
Thanks for all the responses. I lubricated the bearing with white lithium grease about 6 months ago, so I should be good there.
The belt is the original belt so it is about 3 years old. Time for a change?
The motor is also original, and it does seem a tiny bit noisier than it was 3 years ago. How long should a motor be expected to last?
Actually, I was wondering if the how much an acrylic platter would expand/contract with temperature changes. Is this a possibility? The room containing my TT gets very cold when I'm not home and the heat is off.
You could try boiling the belt for about a minute, then re-talc'ing it. That's what VPI recommends should be done every year. If that doesn't work a new replacement isn't much.

Enjoy,
Bob
..just for your information. When my Superscoutmaster needed oil it made a ch,ch,ch,sound. When I called Harry, he said it needed oil and is sending some to me