McCulloch MC200VS Leaf Blower Won't Crank

Hello forum!
 
I'm beating my head up against a wall trying to figure out why my McCulloch MC200VS Leaf Blower won't crank.  Until a few weeks ago, it cranked up every time if I followed the instructions by priming it, putting it on full choke, pulling 3x, putting it on half choke, and pulling 3x or 4x. But now it doesn't even try to crank. I have already tried/done the following, not in this order:

• replaced spark plug
• verified that spark is happening by grounding plug while pull-cranking
• cleaned air filter
• removed air filter completely and tried to crank
• sprayed a little starter fluid into carb and tried to crank
• replaced carburetor completely
• replaced fuel lines
• replaced fuel filter
• held thumb over spark plug hole while cranking...seems to have compression
• removed spark arrestor (entire muffler) and tried to crank...I read those can be clogged but mine seems fine
• replaced gas/oil mixture with fresh

Same result every time. No start. What else is there to try?
 
Thank you in advance.

Go to Auto Zone or Advance auto store and get a loaner compression tester. Thumb over the hole is useless. Hook up compression tester. Set throttle to full throttle and pull 5 or 6 times. If it's around 20-30 psi you might have a stuck piston ring. If it's 100 or more no worries.