Engine Briggs 18 hp Vanguard engine

I have A 18 hp Vanguard engine on a 616 Grasshopper mower that I would know what the compression should be. I have checked the compression and have found that on the left side facing the flywheel I have 135 lbs. on the right I have 120 lbs. I would like to know if the right could be putting pressure in the lower end and building pressure and blowing out the seal on the dip stick tube. Thank you for you time.

Melvin1942

Engine Briggs 18 hp Vanguard engine