Bearings for Revox reel to reel


I need to replace the bearings of a B77 / PR99 reel to reel tape recorder. Do you know what is the best type and brand of bearings for this tape recorder?
microstrip
They are not 606 - the 606 is 6x17x6mm and the PR99 ones are 6x19x6mm - it is the 626. Revox uses a standard quality type, but I read that some people replace it with low friction/low noise much better ones.
You might ask Jack Clark at JM Terchnical Arts in Nashville. He was Studer/Revox's US Service Manager.