For some time my Bacon Slicer starter has been getting weaker & weaker. I've been intending to investigate it but been too busy.
Last weekend at the Scottish A7 Club rally at Guildtown the car became very reluctant to start on the starter so I decided to get on with it.
The problem turned out to be a very distorted brush which was both sticky and contacting 2 armature segments.
I also found that one of the screws holding the brush assemblies in place was missing. When replacing this I realised that the whole brush assembly is held with slots that allow it to be rotated about 3/4" relative to the armature.
Two questions:
1) Why is this adjustment needed?
2) How should it be set up?

The starter now works well.

Location: Melrose, Scottish Borders