How to change carbon brushes in Vax 2000

Question

Since new carbon brushes can be bought for a Vax 2000 (e.g., here) then I guess they can be replaced. Can you give me any tips on how this is done. I've opened up the motor unit and can see the carbon brush units. They seem to be retained by a brass housing. Do I just bend parts of the brass housing until the brush can be withdrawn, or is there some clever way to release the brush and/or housing?  Simon