The carburetor has absolutely nothing to do with the engine's compression. The engine backplate has absolutely nothing to do with compression. Compression is created exclusively in the cylinder.

You must have a leak around the glow plug, a leak around the cylinder head, or a leak around the piston. There is no other reason for reduced compression.

There are some subtle hints in your original post that lead me to believe you've probably ruined your engine by running it too lean:

1. It went dead stick.
2. You had to let it cool down.

You can easily ruin an engine by running it too lean, just once.