This one doesn't have those plugs (611545) in the filter box. I think those plugs you are referring to are on the older OMC F series carb boxes. Mine is a 1993 model 10420 with the metal Walbro carb. I'm glad you mentioned that though because I think you are on to something. I need to check to see if that air box/base is warped enough to cause this because I don't think I have a gasket between the air filter base and the carb. The IPC doesn't call for a gasket there and I usually just stick with whatever the parts catalogue says, but obviously if the surface is warped I would need some way to get a good seal there. I don't think there is any other way for dirt to bypass the filter, other than the two mounting holes, but the screws heads have those holes covered well enough I suppose. I should have checked that out the last time I had that carb off. There probably should be a gasket there anyway because who knows what happens when it heats up. It could be sealing okay when I look at it cold, but when hot the plastic may expand and create openings. I had mistakenly thought that it was just a bad design and the fix would be a remote filter, but that may not be necessary. Thanks guys!Lawnboy 77, you do have the plugs ( 611545) installed in the two round holes at the back of the rectangular F carburetor air box?