Mabuchi (?) Motor repair

[SD45T-2]

I have a can motor, which I believe is a Mabuchi, that doesn't run. It came out of a Pacific Fast Mail H0 D&RGW P44 Pacific of 1960s-vintage.

 

The problem is that the brushes aren't making contact with anything except air and I can't see how to push them down far enough to make contact with the commutator.

 

Because a previous owner has permanently fitted a small sleeve to the end of the output shaft I can't remove the innards completely from the can. As an alternative, can anyone suggest a replacement that has similar dimensions (2mm Diameter output shaft, 16mm casing diameter, and 30mm casing length?

 

Any advice gratefully received.