"What should I set the throttle shaft stop screw to initially?
Was unable to find any "specification" recommended in either the operator's manual or service manual.
Measured the stop screw position on one of our spare TSX-245 carburetors awaiting a rebuild/refurbish for "Sparky" our 51M.
The measurement was 1/8 inch, which is approximately three complete turns from flush.
Take a look at the photo below of a TSX-245 carburetor that was recently refurbished and installed on "Mac" one of our three MTs.
Hope this helps.