300U carb adjustment

Decided to start a new thread on this. I have done a lot of this stuff before but it has been a while and I forget. This tractor would not start this Spring. It was not running great last fall. Plugs had a lot of carbon on them when I pulled them and were obviously very old so I replaced them and the points and condenser. Tractor did not seem to run quite right and would not idle. This carb is different than I am used to. I am used to the Cub-A carbs with linkage to the governor and choke. It is different enough that I haven't figured out what screw adjusts what and I do not know what model carb it is.

One thing I did find out in looking at it is that it has a cable going up to a red knob on the dash. The knob says something like "push to stop". This knob goes to the choke on the carb. The cable does not work in both directions so the tractor has been running choked all along. Guess that explains a LOT! I took a screwdriver and manually worked the choke back and the tractor idles now...just a little on the rough side. Sounds better overall. I would like to play with the idle a little. See can I smooth it out. Any tips to know which screw is which?

Load screw is on the bottom. It controls the fuel flow at full throttle. Out is richer. IIRC the normal setting is 5 turns out.

Idle mixture is the one sticking up at a funny angle, the "middle" screw. It's air bleed so it controls the amount of air. Out is leaner.

Idle speed is on top sticking in from the side.

Don't forget about ignition timing. Changing the points can change the timing a bit.

If its a 361525R91 or 92 carburetor the idle mixture screw is near the top close to where it bolts to the manifold. Idle speed is a little lower close to where the tube from governor meets the carburetor. Unless using the tractor for short periods and light load the screw pointed to front should stay turned out. I forget what's actually called for without looking. Loose packing nut and lightly screw in until you fell it stop, then back out 5.5 or 6 turns and lock the packing nut. If it doesn't have a adjustment screw pointed to the front you have a 361525R91 carburetor that was never changed.
Other poster was thinking about previous model carburetors on the screw locations.

Got it guys! Thanks! Seems to run great now. Good afternoons work.