Audi 80 Idle Noise: Fix for 1Z/AEG (Summer Only)

Hello diesel mechanics,
I've been dealing with this problem for the past 3 years.
Bosch and VAG were unable to help. I even tried a different used pump, as suggested, but without success. Adjusting the injection timing, replacing the crankshaft pulley, and swapping the needle lift adjuster were all done to no avail. Then, I found instructions in this community on how to disassemble the MSW (mechanical injection system) of the VP37 (using DIY methods).
I disassembled my original quantity control valve, cleaned it, and then adjusted the RSW (rotary slide valve) capacity to the previously measured value. It should be similar to how VAG-COM measures voltage, right? However, after reassembling it in the exact same position as the original MSW (within +/- 0.5mm), I still have the same problems. The crucial clue came from a chip tuner: The delivered voltage is too low when the MSW is contaminated with metal particles.
Okay, top cover removed, RSW rotated about 1mm to the right. The sawing noise is now gone, and the slightly elevated idle speed was eliminated by shifting the MSW towards the pump impeller. I'm now satisfied, except for a minor misalignment.
Bosch(SUN) and VAG provide different OT (timing) specifications on the crankshaft pulley. Does the "0" need to align with the upper or lower edge?
Engine: 1Z, Transmission: Automatic, Manufacturer: AEG (Audi 80 B4, Year: 1994).
So, if anyone can make a definitive statement, please share it.
If anyone in the BS area needs help and wants to share experiences, feel free to contact me.
I still have a disassembled pump.
and could optionally attach the appropriate connector (round Audi / elongated VW).
Thanks to the chip tuner and the community for the great help.

Regards,
Andreas Stanzick.