Today, I took a closer look at the engine. So far, everything seems to be fine. However, the area around the fuel pump/vacuum pump is quite dirty.
'I got the seals for it from VW today and I'm planning to remove the pump and reinstall it with the new seals this weekend. Is there anything specific I should be aware of?'
Cleanliness is important when working on it. Otherwise, the pump is relatively easy to disassemble. What exactly is leaking? Is it diesel fuel, or is it more likely to be oil?
Clean everything thoroughly and, after 1-2 days, observe what gets dirty, where it's coming from, and try to find the cause. Then, you don't just install things randomly .