induction motor question

Hello List.

I am thinking of buying a second-hand 90 rpm (geared) induction motor to
use for winding larger coils. I tested the motor in the shop but found a

The motor plate says to use a 15 uF start cap, but when I tried this (with
a known good cap) it wouldn't start unless it was given a turn by hand.
Obviously this would be no good for stop-start coil winding :-)

I don't know much about induction motors, but I'm guessing that the motor
plate does not take into account the extra torque needed to turn the
gearbox(?) How do I fix this? 

Thanks in advance for your help,

Gavin Hubbard