All cleaned up , New brushes carefully bedded and thoroughly run in.
Motor runs sweet, lamp steady, holds speed consistently, until you load it with a cut , then it just droops away to a stall.
I am thinking the Armature voltage feedback function has fallen over . I guess this would tie in with slow ramp up!
(Checked brushes again and they have run in to a nice polish over the faces)
But still gutless.

Anyone had such experience or able to throw any light?