FWIW, My TD-166 MkII that I purchased new in 1984 was mothballed from 1990 until ~1998. All it needed was a good cleaning and a new belt. I have since had it slightly modded, and I am thrilled with it. Once, at a Stereophile show, I asked a panel how much I would have to spend to get a new 'table that improved on my Thorens. Predictably, Mike Fremer suggested something like a VPI Scout, and Art Dudley suggested I keep the Thorens.
I find it hard to believe your belt is okay after all that time in a stationary position. But if the motor isn't getting power it could either be a simple repair (power cord replacement) or major one (new motor). But, man, those Thorens 'tables were built like tanks, like Swiss watches. I would at least get an estimate from a qualified repair facility. I found one through Thorens.