You have a problem. Bad bearings are a wash. Most good guys who restore turntables use a sleeve of teflon in the bearing well. First; how did you determine there is bearing rumble, with a stethoscope? Second you need to find out if they used an off the shelf bearing assembly or one that was custom made. Wherever they sourced the original bearing; that place may still be around. Try some research on the Vinyl Engine site, they should have the info you need. There could be a replacement since there are lots of those tables in use. Since that was an English product I bet Len Gregory has knowledge of it. Try the Cartridge Man site. There are no quick fix's for bad bearings. Let us know.