Hi All-

I've been driving a 66 Porsche 912 since the 70s. In around 2001 I converted to a 2.2 liter Type 4 motor. It's been a great source of fun!
3 years ago I parked the car, intending to do some head work on it and get the car back on the road, but got side tracked by rust worm repairs. With the engine rebuilt as of this Spring, I decided to spin up the motor before I reinstalled it, so I bolted engine and transmission together on my garage floor.

When I applied battery power to the starter, I got this horrible clacking sound, much like the sound of an impact wrench. It does turn the engine over, but this noise sounds like destruction in action. I've tried to attach an MP4 or WAV file, but this board doesn't seem to want to accept either type.
I've torn the starter and solenoid apart, cleaned everything thoroughly, gotten the solenoid contactor pieces and the commutator nice and shiny, but no joy.
I've made sure the battery was charged, and even tried to supply power from my wife's Volvo. Made no difference.

Anyone got an idea of what's gone south here? The starter is at least 20 years old, but it never let me down previously, and it looked pretty clean inside.
The starter is a vanilla Bosch SR-17.
Any ideas much appreciated!
cheers
Adam912. Out.