Then just running the fuel pump a few times and yes the leaking started. When checking I could see indeed the return fuel line, actual the last piece which is the rubber hose with clothing, became soaking wet.
And the gas drops found it's way via the chassis tube exactly above the exhaust tube. Nice. I guess I must have been a bit Lucky here. So time to get it replaced for a new one. Well, after almost 40 years it wouldn't do any harm. It was a bit of a fiddly job but doable. So here the dismantled hose:
Bought a new piece for € 6,- and had it replaced. In the boot I had to remove the clothing to reach the upper part of the tank hose where the return gate goes into.
Turning on the fuel pump a few times and presto no more fuel leaking. Started up the car after being unused for a few months and it almost ran in one go. Nice! Love the sound of it, it ran very well. I'm not sure how much effect this leakage on the fuel return line might had. I would expect little to none. But I sense on my last trip it must have caused the small hiccup / performance drop when driving.
Just had another look into the old hose and removed the clothing. And it came quickly apparent the rubber was aged and broken
Although the weather was very good today I didn't take it out on a test drive. Besides officially I'm not allowed to use it on the road either due to Dutch roadtax reasons. So I have to wait for the 1st of March.