The owners manual recommends filling the fuel tank with a filter equipped funnel to keep water and trash out. Few bother, resulting in the short tubular 1000 mesh filter in the screw in brass hex head 133487 plug in the base of the float bowl rapidly plugging with trash. Frequent cleaning is hard on the 170945 (no longer available) plug gasket. Many have found that compensating for a worn out gasket by increasingly tightening the filter retainer only results in a broken carburator. The tank filter was supposed to cure that. Unfortunately it is treated just like the filtered funnel. Many (who file the instruction manual in the kitchen junk drawer and forget about it) don’t even know it’s their. It plugs from the bottom up. You know it’s a problem when you run out of gas with the tank half full. Of course when the owner cleans the tank by putting in a cleaning solvent with a handful of nuts & bolts and shakes it vigorously, the problem goes away – because they have dumped out the beat up filter with the nuts and bolts. The answer is then to cut the line and put in a clear plastic filter so you can see what dirty fuel they are selling you at your corner "service" station. . . 😀