There is a rectangular connector very near the Ignition switch. Press safety latch and pull apart. Check for green crustys and spray with Zep Battery Care. REPLACE that fuse even though it looked good. A battery can check for 12VDC but have no Amps. Rare but it happens. Possibly your...
I clean off obvious dirt and make 2 or 3 passes against my coarse Grinding Wheel. Same # for other end and blades. It's not the Space Shuttle as Tarryl would say. A gram or 2 out of balance is no big deal.
Tighten carefully after engaging any drive teeth, sharp side Down. Done. Skip OCD.
It would appear that you have a Failure of the Automatic Compression Release (ACR) mechanism.
Simply put, it releases some compression during startup. The only cure is to replace the Camshaft to which this is attached to. First, be sure you can obtain a new one From B&S. Aftermarket ones can...
The wires on a Wire Brush work well for poking through these holes. Some jets on the bottom of the float bowl have a very tiny hold on an angle in the threads.
What Bert said! Not for the newbie or faint of heart! Hook the safety switches back up. Try it with a shot of starting fluid just for giggles. Put all the wiring back the way you found it. Double check that.
Get used to it. Don't cut wet grass. Don't Mulch if you do. It is a normal event. You could try cutting hardwood blocks to suit and use a countersunk through bolt to hold them in the crotch.