Leaky Oil Filter: Causes & Solutions

Hi!
'On my G4 1.9L TDI with 170,000 km, the oil filter cap has recently started leaking. The cap's gasket is new, everything has been cleaned, and no damage is visible. It's still leaking. Does anyone have any ideas? Are there any channels inside the cap or the tube that could be causing this (e.g., being blocked)?'

As far as I remember, there are two seals: one for the lid on the threads, and one at the bottom of that rod/tube. Should the bottom one also be replaced?

Have you recently replaced the oil filter, or did this issue occur some time after the replacement?

Is the lid on tight enough?

...and most importantly, is the filter cartridge installed the correct way?
During the last oil change at the workshop (apparently done by an apprentice), they also installed the filter incorrectly. Then, the mechanic, as required, tightened the cover with 20 Nm, but didn't notice that it wasn't fully tightened. As a result, it leaked oil after driving just 1.5 km.