My briggs & stratton lawn mower leaks gas through the filter area. When u pull the cord and when u turn the blade manually.

Briggs & stratton gas mower leaks gas through filter area when u pull cord or turn blade manually.

Sounds like the fuel valve is stuck open in the carb. You can try a bit of Seafoam carb cleaner with a small amount of gas or just some spray carb cleaner in the fuel line. You can use pure carb cleaner as starting fluid.

Otherwise, you may have to dissassembe the carb and clean.

Come from leaveing stale gas in the mower over winter without running it out or using a fuel stabilizer like Sta-bil.