by chance . your not using fuel more than 2 months old ? no water in your container ? silly i know but amazing how many come in for repair and full of water
you look at the carb you will see a bolt (plug) just off centre on the float bowl remove it and see what comes out water will float on top of fuel that comes out , looks like drops floating on your mower base .
sounds like a blocked jet or water , easy fix if not a blocked jet , see how you go Treegirl
