The screws on the main housing hold the field coils in, and there are few good reasons to ever remove those. The wiring is going to be very stiff now and unless you want to chrome the barrel (?) the coils should not be disturbed. An impact driver will be required to remove the screws. They probably have threadlocker on them, as it is very bad to have one come loose - they carry the motor torque back to the barrel... the starter motor will be torn to bits inside if one comes loose.
I'm not sure how that wire is attached, I would guess it's resistance welded though. Get some black heat shrink tube to fit the cable and it will look pretty nice, plus add extra insulation.
I've never seen a CB starter motor actually wear out. I did replace one with stripped gears (CB77), probably the (failing) starter clutch had caused that.
Since the brushes are good I would suggest you just clean it up, dress the commutator a bit, lube the bearings, and it's good to go for another 40 years.