It needs to be replaced.
Exhaust leak possibly...
No, seals are cheap, engines expensive.......
Dirty or stuck open needle valve in carburetor.
Inlet needle in carb sticking open; it runs in through the carb.
A lawn mower may leak gas from the air filter due to a carburetor issue, such as a stuck float or needle valve. This can cause excess fuel to flow into the air filter, leading to leakage. It is important to address this issue promptly to prevent potential safety hazards and damage to the lawn mower.
Oil on a lawn mower spark plug can be caused by a few reasons, such as a worn piston ring or valve seal that allows oil to leak into the combustion chamber. This can lead to poor engine performance and difficulty starting the mower. Regular maintenance and checking for leaks can help prevent this issue.
If you tilt the mower to get at the blade for sharpening, or go down a particularily steep slope, gas will run from the tank out through the filter.
If your lawn mower doesn't have a drain plug, you can tilt it on its side to drain the oil. Make sure the oil is cool, remove the oil fill cap, and tilt the mower so the oil drains out through the oil fill hole. Be careful not to tilt it too much or oil may leak out of the air filter. Once the oil is drained, refill the mower with the appropriate amount of new oil.
By backing the choke out I assume you mean turning it off. If it stalls when the choke is off but runs while it is on then you have an air leak somewhere
fill tank, to top of neck, watch the leak area, [don,t start it]
There are products at your local auto parts store such as Epoxy Ribbon, JB Weld, and others that don't require heating you can use to patch the leak. Be sure and follow the directions on the package. You can't BEAT KENT'S ALL IN ONE.
I would start at the carb take the air filter and clean it .Then take the carb apart and clean it also might be stuck linkage. Good luck