You won't get any disagreement from me on the desirability of being cheap, Lachie. The job can be done with the later manual, but it will be more difficult. You need to start on page 48 of 336, and remember, your engine is a 92900 series. In particular, it is not a 92500 series: that has a Vacu-Jet carburetor, still with an automatic choke, but with no diaphram and consequently less complexity. I suggest you do not follow the overhaul procedure as such, since that would require various new parts that would be difficult to get. The objectives are to inspect the diaphragm and replace if necessary; to clean the fuel intake screens, especially the one on the longer tube which is the fuel pump pickup - but only removing the tubes if they are the screw-in type; and to clean out the jet and the metering holes, plus miscellaneous fuel and air passages. You will need a spray can of carburetor cleaner, complete with the long thin tube that comes strapped to the outside of the can.
Remember that your engine has an automatic choke, not an all temperature automatic choke, it has a Pulsa-Jet carburetor, not a Vacu-Jet carburetor, and it has a pneumatic governor, not a mechanical governor. At this point I can't tell you whether you have a zinc (metal) bodied carburetor or a Minion (plastic) bodied carburetor, but I think by 1982 most of them were Minion.
I suggest you now read the manual, identify the sections which actually apply to your carburetor, and remove the fuel tank and carburetor from the engine. Then remove the carburetor from the fuel tank, take some pictures without doing anything else, and post them here. Then we can discuss the situation before proceeding. I'm hoping you'll find a bunch of grass and crud blocking the intake screen of the long tube. If you do, we can talk about how to clean it without having to buy parts to put it back together.
