^^^^^ What he said. Worn or not floating are the two big issues.Like flyweight suggested:
Get a carb kit and check/replace needle/seat. Also, it is *critical* to check the float level.
You can check float level with a drill bit, based on the specification of the float level spacing.
Also, if the float is plastic, ethanol fuel could have damaged it, causing the float to fill with gas and "sink" causing flooding.
You can check the float by ensuring it "floats" on gasoline or water in a glass. Removing the float requires removing the float pin and carefully removing the needle from the float tang.
For example, if the float level is 5/16"--
1. Get a 5/16 drill bit.
2. Turn the carb upside down, so the float assembly and needle will be "closed" against the seat.
2. Slip it between the float and the carburetor metal body.
3. If there is no "gap" between the float "top" and the carb body, then the float level is "good"
4. If there is not enough space, or too much space, you will need to adjust the float tang-- where it connects to the needle
5. Use a small, precise needle nose plier and very gentle movements to adjust the tang!
Clean out all the other passages.
Note: Ethanol fuel is bad for small engine carbs. Use fuel treatment (e.g. Sta-bil).