IRS: the final

The last 2 weekends were a rollercoaster of ups and downs. Last week Sunday my friend Rui and I installed the engine. Upon the first start a shreeking noise couldn't be ignored.
As the engine, flywheel and starter were the same as before and the sound appeared to come from the gearbox, I suspected the gearbox to be faulty. So, engine out again! Nothing in the bellhousing, no rub marks, no metal flakes. All looked fine. Then I removed all the type 3 cooling stuff to check for signs of rubbing or wear. Again, nothing- everything looked perfect.
Then I organized another gearbox - a big Thank you to Thomas - and mated the egine to the box, outside of the vehicle. Upon start the same annoying sound appeared again!
Was there something wrong with the engine? It ran fine before. The only thing I worked on was the oil pump. To remove the oil pump, all cooling tins and propellers had to be removed again! Then, at least there were minor signs of contact between the gears and the oil pump cover - but this couldn't be the source of the noise.
As I was certain the engine MUST be o.k. internally, I reassembled it yet again - Thank you to Ralf for the spontaneous help!
Sunday morning, all wires, the header, exhaust and heater pipes had to be mounted again.
Guess what, the same story again. Shreeking noises. Then Olli stopped by, checked the situation and pointed towards the starter - which was also a possible source of the noise. So, we started the engine and removed the starter with the engine running and: The noise was gone!
So I harvested the Streaker and used it's starter in the type 3  with instant success, the engine ran beautifully, no disturbing noises!

Finally, I used the "noisy" starter in the Streaker and it works perfect - just like before in the type 3! I don't know exactly why, but I don't care anymore, both engines start with no issues- success in the end!
Tomorrow will hopefully see the Fastback back on its wheels for a proper test ride...