How to diagnose a blown Corsa windscreen wiper motor?

Vauxhall Corsa 2003. The motor is dead after the cold weather. I have a 6 week wait until my new one arrives from dealer. I want to try to patch the one I have for now. Linkage is fine, and when disconnected the symptoms are:
a) Stutters for about 10 seconds, then blows the fuse.
b) Not likely mechanical, and brushes/commutator seem visually fine (have continuity).

How is it blowing the fuse? A direct short? What is the stuttering? I suspect a circuitboard component, there is evidence of overheated insulation on the yellow wire, after the connector, to the motor itself.

Is there a way to diagnose which component is the culprit? I have basic electronic skills and I am about to completely strip the thing. Having it work on just any setting would do for now.

GB
January 2010