CLEAN THE CARB
Bad/old gas will varnish up the insides of the carb itself and crap from the fuel tank will plug up the jets.
If the machine has not been used for a while, or it's NEVER been cleaned - it's due.
I'd start by running some SEAFOAM thru the fuel system and replace your fuel filter (if it has one- if not add one)
It's not that hard to do, just take your time and pay close attention to how the carb comes apart so you can put it together again. Also be mindfull that the screws are SOFT and strip easily.