T4 Diesel Pump: Replacement & Repair

Hello, I had to replace the diesel pump on my T4 1.9TD, manufactured in 1997.
Was anstelle der defekten Pumpe eingesetzt werden konnte, war eine identische, funktionierende Pumpe.
built-in.
Everything is marked, as far as I've adjusted it, timing belt and crankshaft position.
Unfortunately, it won't start.
You can see the pump drawing in fuel, but nothing is reaching the pressure lines that go to the injectors.
I'm slowly starting to feel lost.
Best regards,
Martin.

Hopefully, I've found the problem: the magnetic switch is stuck.
Best regards,
Martin.