Thanks for clarifying that Redeye. It seems like you can focus on lean mixture. If it happened suddenly without you having done anything to the carburetor, the O rings seem like the most likely problem. Someone posted the other day that if you smear a little engine oil on them when you are installing them - especially the one that seals the side of the crankcase, under the starter - you have a better chance of them staying in place rather than popping out of position. I used to do that routinely with O rings anyway for almost all applications, for various reasons, though for stationary O ring seals I usually used light grease because it's stickier.
Please tell us what happens. If you still have the problem after replacing the O rings carefully, we can go through the fuel tank/fuel line and carburetor processes. (Have to get a plastic Victa carburetor guy for the last stage of that, of course.)
