It’s a 4mmX9mm flanged bearing...slip fit...be sure to get whatever sleeve goes on the front end of any open ended shaft.....I believe this loco uses two shafts, with a secondary dog bone between the two shafts. So the very front forward shaft will be open ended....you’ll need that sleeve to set the shaft end play. With out it, the forward shaft will rock too much between the bearing ends, and you’ll destroy the worm wheel in short order....The sacrificial lamb unfortunately, is the worm wheel, not the worm shaft.....the worm shaft is as hard as darn it, the worm wheel is a much softer alloy....
Pat
