Rick wrote:

Older engines were "Easy spins", which held the intake valve slightly
open for a small portion of the compression stroke, so the usual methods
of checking compression won't give accurate readings (and Briggs did not
publish figures). For those engines, Briggs recommended rotating the
flywheel in the opposite direction and looking for a sharp rebound.

Yeah, the backwards rotation is the way that I checked it.

Do you have the crank connected to the load? I'm wondering if the
flywheel needs the added inertia of the blower (like a vertical shaft
mower needs the blade). ...

Ohhhh ... yes! Never occurred to me, but you're right. I have a
vertical lawn mower engine used without the blade I occasionally get the
_same_ "kickback". I'm gonna' try it with a load.

Thank you,
Bob