tachogenerator

Hello All
I have picked up a G E tachogenerator hoping to use it as a spindle
drive motor for my mill.
It is a pm rated at 100 volts per 1000 rpm.It is apprx . 7 inches in
dia. and 10 inches long,has
four brushes 180 degree spacing. When I apply 100 volts it
rotates ,but with a 2 inch pulley
on the shaft I can stop it by hand a turn it in the opposite direction.
So my question is , is there something I can easily do to this motor
to increase its torque?
I also notice the magnets for being quite large , do not seem very
strong.

Thanks Rick