03-02-2022, 10:44 AM
Hi Graham
I'd be inclined to check the brushes first, and make sure they are free to move.
It's a long time ago now, but I seem to remember that part of the current path in the brush holders is via rivets. These can be mechanically tight, but get corrosion under their heads. With the high current drawn by the starter, the slightest extra resistance has a significant effect. I think I left the rivets in place but soldered a braided link in parallel.
The winding resistances will be maybe 10 or 15% higher when the starter is good and warm, which will also reduce the current slightly.
I'd be inclined to check the brushes first, and make sure they are free to move.
It's a long time ago now, but I seem to remember that part of the current path in the brush holders is via rivets. These can be mechanically tight, but get corrosion under their heads. With the high current drawn by the starter, the slightest extra resistance has a significant effect. I think I left the rivets in place but soldered a braided link in parallel.
The winding resistances will be maybe 10 or 15% higher when the starter is good and warm, which will also reduce the current slightly.