PaulD wrote:

Ether or anyone else who can answer: Do you think the possible
valve problem is causing the cranking problem? Or do I still maybe
need a new starter?

It's difficult to say without quantitative information. Can you
quantify how fast the engine is cranking? Put a piece of masking tape
on the rotating screen. Is it slow enough that you can count the revs
while somebody else keeps time?

Or, how difficult is it to pull the starter? Your local parts store
that charges batteries for free sounds helpful. Do they have a test
stand for testing small engine starter motors?