Finished rebuilding my winch after I pulled it down to work out why it was intermittent. Turns out last time I rebuilt it I used red urethane paint on the brush housing which ended up seizing the brushes, so after working for a little while the brushes shortened enough to no longer make sufficient contact with the armature. Long story short it's all back together and functioning 100% on the bench. Now to finish putting it back in the bull bar. I also am going to run an air horn compressor through it this time so should also stop water entry and run cooler :)