Williams GP9/7 motor mount/pilot screw size?

@Magicland posted:

Someone else had this issue about 5 years ago, but never got an answer. Attempting to replace a motor in a Williams GP9. Now, Williams no longer makes motors for these, but they do make a few "universal" motors. The worm gear on the motor is slightly too long, but was easy enough to shorten, and the pitch is the same. The problem is mounting it. The motor mount fits fine, but the screw (which it doesn't come with) isn't the same size as the old GP9 mounting screw (which I believe is 3mm). The screw on the new one ALMOST fits a 6-32, but it won't thread in correctly. It IS the same exact size as the screw that mounts the pilot to the truck, although longer. That'll screw in just fine, but of course, is too short to reach the motor mount through the truck. Does anyone know what size that screw is? 4mm is too big.

I've taken similar things that I needed metric screws for to my local Ace hardware that has quite a selection of screws and find the screw the correct size and pitch.

Try a search: Whitworth 55 degree/Metrisch 60 degree, thread gauge.  Also Wilson or Wolpert.  I have one in my tool box, not sure where I purchased it.     York train show, there was always a couple of venders with an assortment of tools, related to model railroad.