YOu could short block it.
The thing about the compression test is, it just tells you if you have compression. If you could have a leak down test done, this would tell you if you have a valve train, ring, head problem.
If your unit was on my bench, I would have tested for spark, a plug can fire outside the head, and not fire under compression. I have a tester for checking the secondary windings in the coil. A coil can fire from the primary winding and not the second. Then chacked for fuel. Checked the valves, then if it wouldnt start, do a leak down test. Briggs cams are soft all engs for the most part have some type of comp relese on them. Even big chainsaws have compression release buttons on them.
Im not a big fan of briggs, notice I said briggs, not vanguard, theres a differance. If the mower is in good shape Id replace it or short block it. I do alot of short blocks with briggs. When you do it just be sure to put all new filters on it, cause it basicly is a new eng. I dont know what they cost, I dont see prices but I get paid 2 hours to do one.
If it has an elec pto be sure it goes back on right, theres a 300 mistake, ask me how I know. And youll more than likly have to put a new drive pully on, most times they are rusted to the crank. Heck your there do a drive belt too and check the idlers, espically that lone one by your left foot.
Let us know what they find.
