dmitr 79 psi is good if using the tester with the longer rubber tube ,I have had tons of mowers that run at 50 psi. From memory the short tester will be about 10 psi more. I've seen a lot of mowers that people use until they are down to 40 psi and had mowers run for 10 years at 50 psi as long as the bore and rings aren't scored.
I usually run them on start ya bastard and if it runs then it must be a carby fuel related problem ,if it doesn't run on starter fluid it's spark or crank seal problem or blocked muffler or port.
I usually make sure the 3 starter bolts aren't loose because if they are loose the crankcase can leak.
There are 2 seals that must seal on the starter ,one is the starter housing large o ring ,the other is a seal in the centre of the starter then a bearing seal under the motor.
One way of checking if the crankcase seals are leaking is a Vacuum test.
Some times when the crank seals are bad you can put some oil in the plug hole then replace the plug ,spin the motor over and oil leaks onto the outside crankshaft near the blade plate ,a little difficult to see with a powertorque motor as the flywheel is in the way and is why a leak down test would be better.
If I want to rule out the decompressor valve as a problem I would remove it and put a spark plug in the hole for testing.
