Having just finished the process, and having access to the service manual, I thought I’d share my experience in the form of a how-to. This applies to a 22261 Commercial, but would be similar for any DuraForce.

Supplies needed:
-can of Carb Cleaner
-#78 and #67 wire gauge drill bits (got mine at Grainger for two bucks each, available within a #61-80 set elsewhere online)
-pen vise / micro chuck to hold the bits (Harbor Freight had a cheap one, Sears had a nicer one with assorted bits for $9, including a #66 if you want to double overbore your main jet)
-cutting/tapping fluid
-Loctite 242 Blue (or a medium strength threadlocker that resists vibration)

Optional items:
-the 4 gaskets which will be encountered are optional (I didn’t replace mine, especially since the bowl gasket was $20)
---gasket part #’s are:
-95-7613 behind the air filter box
-94-5795 on both sides of the rectangular heat shield between the carb and the engine
-98-1362 bowl gasket within the carb
-a tool to measure RPM, such as a Tiny Tach or a multimeter w/ attachment

Procedure:
1. Thoroughly clean the airbox, carburetor, linkage, and nearby areas with carb cleaner. I made the mistake of not doing this and wasted a lot of time individually cleaning parts of grass clipping residue afterwards. Save yourself a lot of grief.
2. Take a good look at how everything is assembled. See the orientation of the carb, the linkage, and the fuel lines.
3. Remove the air filter cover and filter. Cut off the fuel supply and remove the fuel lines from the primer bulb and the carb. Unbolt the throttle linkage at the air filter. Remove the two air filter screws within the airbox and be prepared for the three gaskets to dislodge.
4. This next step is delicate as the wire spring connecting the air vane and the linkage is delicate and should not be stretched. Rotate the airbox and carburetor down, back, and out as a unit without putting strain on the wire spring. Once separated from the mower, they can easily be separated from each other.
5. Clean the outside of the carb again before opening it up. The pilot jet is beneath the sticker on the side. Peel back the sticker and remove the jet.
6. This jet will be bored out with the #78 bit. The bit is not unlike a sewing needle, and therefore rather fragile. I was able to stand the jet small hole up in the middle of a die I had sitting around. Anything to stabilize it up and down will do. Then add one drop of tapping fluid over the hole, and gently spin the bit with light pressure to bore it out. It took about 5 minutes, occasionally backing out the bit and adding more drops of fluid. Blow out the jet to clear the shavings, then reinstall with one drop of Loctite 242 blue on the threads. Replace the sticker.
7. Next will be the main (hi-speed) jet. I set the carb on a table with the four screws pointing sideways. Remove the screws and carefully remove the cover so as not to damage the bowl gasket. Remove the metal screen cover (fuel filter) from the end of the nozzle. The main jet is within the nozzle. DON’T UNSCREW THE NOZZLE, just the main jet. The boring of the main jet is less delicate since the bit is larger; I simply held it between my fingers while spinning the bit. I had good results boring out with the #67 bit, though the #66 could possibly allow more improvement. YMMV. Again, one drop of Loctite 242 Blue on the threads before reinstalling.
8. Installation is the reverse of removal. Be gentle with the air vane spring, and note that the rectangular plastic tube which interfaces with the airbox must be installed before the two airbox screws.
9. After starting the mower and bringing it up to operating temperature, recheck the no-load RPM. Mine went up, possibly because I stretched the air vane spring a little bit, and maybe because it’s running richer now. Use a Tiny Tach or multimeter w/ tach attachment to reset to 3000 rpm. RPM adjustment is accomplished by clicking the white-toothed air vane wheel counter-clockwise (reduces RPM) or clockwise (increases RPM). I simply straddle the mower and use my two middle fingers.

My result was a cure of the surging which developed after a season of home use (25 hours). After rejetting, it surged very lightly for about five minutes before clearing itself out. Now it purrs.

Happy mowing!

Would there be a benefit to 3400 rpm or higher? Seems to already hack through everything pretty well at 3000.

Thanks to an earlier member's help with boreing out my Lawnboy carb-it made all of the difference in the world.

The latest link about putting Locltite to hold the jet in place may be my problem now with the LawnBoy in the shop.