Technics SL1200 Footer thread size?

Thanks for all the helpful advice. Levelling the rack is not a very convenient option. It is a double-wide (TV-type) VTI rack on casters. The casters are needed because I need to be able to roll the rack out for access to the rear of the gear, and also to clear a sewer pipe cap that sticks up out of the floor. Someone also suggested placing a butcher-block type platform on nylon wedges, apparently available at hardware stores, to level the 'table. But I may try the sorbothane idea Tvad posted. It will be a little while, probably, but I'll keep y'all posted.

in nightclubs we used breeze blocks with concrete slabs on top with zero feedback

A tip I got from a nightclub DJ was to use those wide gel pad wrist rests for computer keyboards. I got a pair and use them under the heavy butcher block cutting board I use as a platform. But I also have a layer of Vibrabpod Isolators and Cones plus threaded brass cones between the turntable and the top of the butcher block.