Update
I just finished installing a new Gear reduction starter ´LUCAS´(Lord of the Darkness!) from SNG. Installation was quite straightforward as the unit is much lighter (3x ?) and smaller. I did even manage to put back the plastic cap covering the hole on the transmission tunnel, which is inserted out-in and almost impossible to reach from the outside .
I still need to go for a spin but the engine turns well with a more ´civilized´ sound. Moreover, it draws less current and seems to turn engine faster. (Although I have never had starting issues with the original motor - until it failed)
Will I have no problems after my test drive hopefully during the wend I truly believe this is the way to go.
This is why:
You can see the original motor in one photo. All seems visually impeccable . Even a simple test with an ohmeter did not detect a problem (for continuity and shorts of the armature), but the armature was actually dead after being tested in a ´growler´.
The motor has plenty of insulation components, and on V12 after 50 years they all become brittle. One day they will fail, it is a matter of time - and luck. Rebuilding it would be far over 600 Euro (or USD) and you’d need to find a reputable company. You simply should not rely on a motor baked for 50 years in a V12 engine bay.
A 100 USD rebuild (as written here on the list) is basically a fix, cleaning, new brushes or solenoid change at most, but you will still get a baked motor back.
That would be ok if the motor could be easily removed or on a manual car, but on an automatic it will leave you stranded. I see no arguments to take that risk.
That said, my old Unit is well packed and will be part of the car - up to the owner then to rebuild it if he wants and put it back, fully reversible .
I hope this helps !
You can see that at the end of the windings in the armature the insulation is partly gone , touching it it will crumble …this is probably what happened inside , although not detectable with an ohmeter but under high currents only :
