Have a Agway Snow blower model 523.Plug from Carb fell out.Replaced and now the engine idle goes up and down.The carb was replaced last year has only a few hours running time.5 hp Tecumseh motor. Ran good until that plug fell out.Carburetor P/N 640084B

I have no idea what plug you mean but I would say that there was either a spring or gasket that you didn't put back with this plug or that it needs to be adjusted.

Hi,
I gather you mean the welch plug that govers the low speed circuits, so the cure is to seal the edges of the replaced plug with fingernail polish to seal it and prevent air slipping past it.
Peace,
Clarke

The float bowl has a needle style plug with a spring and small washer. You need all three and can be found at most lawn and garden centers that sell and repair garden equipment. Adjusting this screw plug will affect the running of your engine. Start with tightened up firmly and the releasing about 1 to 2 turns.

Hi,
I gather you mean the welch plug that govers the low speed circuits, so the cure is to seal the edges of the replaced plug with fingernail polish to seal it and prevent air slipping past it.
Peace,
Clarke

Sounds like a plan. With all this snow coming.. Will try it.. By the way thanks for your help.. Don L