1987 Marathon motor reassembly

[KOG]

I've suffered a field bolt burn off due to corrosion and loose connection on a cart I bought in badly abused condition. I've disassembled the motor and found that the bolt in question is spotwelded to a field lead. Tha can probably be fixed, but I haven't figured out how to reassemble motor. Problem is how to deal with the brushes. The only way I can figure to do it is to remove the drive gear from the end of the motor, put the commutator into the bushes, slide the motor housing over the rotor and bolt on the brush end plate. Then assemble the drive end plate and reinstall the drive gear.

It can be that difficult, can it? The service manual posted on line here covers later models and sort of glosses over getting the brushes back on the commutator.