Agree, working of the B&S compression release system is VERY dependant on the valve setting being right.
If you have one that the starter struggles to get cranking, adjust the valves.
You will find the valve setting at .o10 + loose, readjust them to .004 and it will turn over like new.
Not quite briggs tech procedure, but adjust each valve while it's partner is wide open, will get it very close. With the sparkplugs removed, it's easy to turn the engine by hand to get the valves in the correct adjusting position.