(quoted from post at 02:29:05 12/20/17)
Its hard to believe but not unlikely the carb could have problems as I took it out of the box and installed it made sure there was no crap in the fuel line and installed the filter before running fuel to the carb just in case I didn't get all the rust and other things out.
I wouldn't be too quick to rule out a faulty carb seeing the number of posts with repop carbs problems.
If you determine fuel flow through the float jet is adequate, next item to eliminate would be float level. Should be 1/4" between bottom of float and carb housing with bowl gasket in place.
Yesterdays tractors didn't have a replacement for the schebler that was on it so I had to send the carb that was on the tractor down to ohio where they get their carbs rebuilt. I didn't want to buy an aftermarket and we were not in a hurry to get it back that's why I did it this way.
Initial setting should be 1½ turn out on the side pointing idle/air adj. screw, and 1½ turns out for the main fuel needle. Start at idle speed (450-500 RPM) and let the engine warm up to operating temp then, adjust the idle air screw, in to get the highest smooth idle 1/8th turn at a time and listen for highest RPM. After you set the engine running at idle, then you can set the main jet for max fuel needed to run at WOT under load.
Keep in mind, the idle jet needle on an M-S TSX carb is an air control needle so tuning it in enriches the idle mixture whereas the power jet needle turning it in leans the mixture.
As you are helping out a neighbor, send me the OEM carb you removed and I will be glad to rebuild it (Email open in Modern View for address).