My advice: Do not pass goal, do not start engine, do not have to replace heads and valve gear. Get new shroud . Its fit around the fan is all that is between your briggs and a barbeque.
Just checking: this is your landlord's mower, correct? Maybe check with him/her to see about proper maintenance; wouldn't want you to get slapped with a fee for failing to properly maintain it.
My mower can't mow continuously without having to use the break as a clutch. The blade sounds like it's about to fall off and has a hard time cutting my grass. The is always on the verge of stalling out.
The mower is a Craftsman ridding mower and the engine is a Briggs and Stratton.