Teflon tape might work but, for how long and how well? I had a problem with an air mixture screw a while back on an older US car and ended up getting another screw, The housing was fine but the screw was slighty striped. I don't know where to get one unless you can find a good used one. Are the threads on the screw and/or the housing worn or stripped? Does the screw wobble in the housing?
Rolf
1966 230SL Auto
1992 300D
1991 FLHS