If the belt is not too badly stretched, you may be able to get some more life out of it by putting into a bag of talcum powder and shaking it around. After only 3 months though, it sounds more to me like it may be a bad belt. Give Sheila at VPI a call and explain the situation, be ready to give her the serial number of the table though. They may help you out and just send you a new belt. I have had nothing but positive experience whenever I have had to call.
