VPI 16.5 Problem

Hi, picked up a used VPI 16.5 here on audiogon--eventually the law of used had to catch up to me, I guess. Worked great for about a dozen albums, but since then the vacuum seems to overpower the turntable--having no knowledge of how the turntable works, it is acting like there was a loose drive belt. So, vacuum really, really works, motor for turntable works, turntable spins (though sometimes starts slowly and then speeds up to normal operating speed), but when both on, turntable stops rotating (motor continues). Any ideas before I take to a repair shop? Thanks very much.

I have 12 beautifully cleaned albums, though.