just force....pushing from the backside with a screwdriver (as written)
I had the carbon holder made by FibreLite (I had some
help from another forum member, did some adjustments and an autocad drawing was made out of it). Feel free to email fibrelite (Stephen) and use my drawings (prices are ok).
Omori meters can be had at a Subaru
dealer (very expensive) or the states.
This setup is also delivered for Audi and will cost an incredibel amount of money, I did the same at roughly half the price....
In this way the vent funktion will stay roughly intact (with a 52 mm meter it won't)