After Kensmachine pointed out the diffweence between high wall and low wall trigers, I started verifying what is in each of my 15 walls.  I did have a low wall that I had installed an MVA SST in.  It was a high wall SST and stuck out below the tang quite a bit.  Since I had acquired a couple of what turned out to be low wall SSTs, I managed to replace the MVA one with an original in that low wall.  I think I have finally stopped cussing
What I did find is that the MVA adjustment screw does not fit in any of the 4 original triggers I have.  I did find one original screw for the low wall trigger, but I need to either find more original screws or a tap to match the MVA screw.  I have reached out to Ken to see if he has any.   
Does anyone know the size of the originals?  thay seem to be 4-something as are the MVA ones even though the thread pitches are not the same.

Thanks

Jack