I have seen rebuild kits for these, but I can't recall where. It's very possible it was on one of the European parts sites. Maybe try searching the part number together with "rebuild kit" for example. Google translate is your friend.
You could also take a chance and take it apart. You will no doubt need to clean a lot of grit out, but then you can either put it all back together, or take the wear items to your local auto parts store and roll the dice on finding replacements.
EDIT: Actually, I saw it at EI. Part # 0014303760 and $83. Not sure if it is correct to the FLU, but EI wouldn't sell you something that isn't for your vehicle. I suggest you give them a call.
That is great, you have helped a lot. I found the kit using your part number it came right up. I had just given up, and was going to seal the air line from the venturi valve with a homemade gasket.
I had searched for the part kit all over, with no luck. Closest I came was a company in turkey that went out of business in 2017.
I took it apart, and in the process broke one of the plastic rings that go on the piston.
I actually think that all the "O" rings were OK, and that it was just dirt holding the valve open, but it was too late with the broken piston ring. The valve was the only part that was showing wear.
The part number on the kit matches the part number for the kit specified in the parts TM (P/N I 86741). The only thing that I see is different is that there is an extra hole in the gasket pictured. The one that came off the SEE shows a circle of sealant at that location, but no hole. nor is there a port at that location.
Thanks Again.