I think they are pretty standard bearings...? the words 'magneto bearings' ring a bell.? Not sure of the exact spec (anyone?) but I think there are plenty of available sources depending where in the world you are.?
I had my cartridge apart when I bought my Uni but could find no play or roughness in the bearings. I cleaned them with paraffin and repacked with automotive lithium grease and reassembled.
Regards, Andy
