I am weighing up a couple of options. I could get some M3×0.3 screws made, or drill out the wehnelt and tap it to M3.5×0.35, which is a standard metric fine size.
Also, may I ask the SX100 community from where you obtain your filaments?
We currently get ours from Ladd, but they are mostly the style where the tungsten wire is welded to the same side of both posts, rather than different sides of each post, and it seems that we don't have enough adjustment in the wehnelt to centre some of the 'same side' welded filaments. I am thinking of getting the workshop to bore out one of our wehnelts to increase the diameter of the hole by ~500 µm to get more adjustment. Could this turn out to be a bad idea?