I changed out a set on a used 540c 9xl I bought - brgs felt gritty. The removeable bell end was not a prob - they are light pressfits. That end was done in about 5min.
well i think im going to do the dual 6xl motors on dual 4cell lipos and im goign to change out the bearings in them just in case i want to up the amount of cells im using. like maybe go to 5 or 6 cells.