I recently bought another Tanaka ECV 4501 that would not run. The chainsaw had about 130# of compression and I did get it to run after cleaning the carb.
I might add that it ran really good but I had already discovered that it had a (not so good looking) piston. I took the cylinder off and saw that there was some scoring of the piston but the cylinder cleaned up like new.
While searching for a piston, I discovered that many hobby shops carry a replacement piston that is used in some ---(airplane/boats)-- or something, and it is for a Fuji IMVAC engine.
When I received the piston, I discovered it was an exact match but had a dome that was polished really good, and it was marked Hitachi.
I have no idea what other engine parts would be the same ---might be that they adapted basically the same engine for this sports application.