I tried to replace one on a 190E, but isn't not as simple as I thought.

Do you need a special tool/machine to take the knittings out and put new ones in, there is no screws there...

Would any mechanic be able to do that or should I go with the dealer to get it done. I already go the entire fuel/air intake module out.. (I thought that there will be nuts on the inside of that thing)