Finally got around at looking at my sons other donated loco properly ... a Triang R357 Class 31 Diesel Electric Brush Type 2.
The X.03 motor looks as if it's had a rough life.
The wheels look as if they have never been cleaned.
The collector units on both sides are bent out of shape and badly 'kinked'.
The magnadhesion magnets has picked up several track pins which have been cutting into the armature plastic and gears.
The main problem is the magnet screw ... it appears to just spin around within the nut ?
The idea was to convert to DCC so the collector units can be temporarily abandoned and the decoder wired directly to the wires from the other bogie and the brush arms.
The damage to the armature does not look too bad and a test of the motor suggests there may be some life left in it.
What to do about the magnet screw ? Drill off the nut and replace or ...... ?