I bought mine April 07 also with Briggs motor. This happened to me last year and the push rods in the one cylinder got bent. The dealer rebuilt the one side and one year later my engine blew again. Mine started hard like this a few times before it blew for good. Sounds like your on your way. I now have a mower that cost $4,000 and is worth nothing unless I buy a $900.00 block. I think this residential model is junk. I have had nothing but four years of problems.

Look at smallenginewarehouse.com
You can buy a complete engine for that.. Luck