How do I adjust the speed on my Linn Sondek LP 12?

I took the outer platter off to make a template for a home brew turntable mat (I know that most people would say to use the felt mat but it's an easy way to fuss with VTA and to try new things) and I turned it on to watch where the belt was riding on the inner platter (down low towards the bottom). Anyway, when I put it back together the speed is much to fast. The 'table is an 1984 lp 12 with Vahalla power supply. I bought it used from a Doctor who did not have much time to use it because he moved a lot and was too busy. He "stored" it in the basement for the last 4 years. I've had it for two months and it worked great until yesterday. I have a copy of the set up manual but I wonder if it there is something wrong with the Valhalla that can not be remedied with minor adjustment. If so, does anyone know of a good Linn set up tech. in the Berkley Ca. or greater Bay Area. And finaly, should I consider a Circus up grade while I have it in the shop? I assume it is going to cost me upwards of a $100.00 just to have them check it out and "tune it up". If I go the upgrade ($325 ??)I will essentially get the first $100 of shop time "free" and perhaps have better performance in the end. I paid $675.00 for the table with Ittok LV II and Koetsu Rosewood cartridge with little use. Any feed back or opinions would be helpful. Thank you.