itty bitty
Yes, I guess it's possible that the carb is bad. I have a couple of boxes of parts and I'm sure there's an extra carb or two in there. I also thought that the intake block might have a leak but haven't tested it out yet. I may rig up a pressure vac test for this saw since I have several now.
I'm no expert on the EZ's just lots of hands on experience.
When I first started fiddling with some of the older erratic acting doggy ones I also suspected and wondered about the intake block and reed valve area behind the carb and have yet to find a bad one. Seems kinda bullet proof area behind the carb. Most generally I've found it's either the HDC carb or the points. (on the points/condenser ign's)
Also when cleaning and kitting the HDC carb be sure and clean/probe the
4 itty bitty holes under the metering lever cover plate. Here is a link to give you an idea, note L1, 2, 3 and H1. I can use a itty bitty tag wire for the L's but have to go to a carb jet cleaning set and use the smallest one to probe the H1 hole. H1 is the gas feed hole for the other 3, I think. If H1 is clogged the carb won't operate at all, engine won't start or run.
If any one of these itty bitty holes is restricted the carb won't perform correctly. See fig 11 and 12. (they are the Low, High and intermediate feed holes for the engine)
http://www.drystacked.com/Walbro Carburetor Theory 27Jun2010.pdf
This is not a exact HDC carb but it will give you the idea. I cannot seem to locate the exact HDC carb pictures of the transistion holes at this moment. I also do a pressure test of the gas intake after kitting and it should hold at least 3 lbs pressure. I think it's spec'ed at 10. If it won't hold pressure the needle or seat is most generally leaking and the HDC carb will flood or sometimes before kitting if a HDC is running real rich I pressure test before taking the carb apart.
At least you know when you get a EZ up and going it's a good little saw for it's size and built to last for Bubba vs the disposable plastic junk of modern times.
Just takes some patience fiddling with re-stabbing the carb plus few other things.
See my tips for re-stabbing the HDC down into the air box. My tips will save you lots of time and pain especially tieing the throttle a full open and carefully reaming the throttle linkage hole at a 45 degree angle with a 3/32 drill bit or sharp pointed hand reamer to give the throttle wire a lead in channel and glue to intake gasket to the carb on one side and oil the other side so the gasket is re-useable and stays aligned during re-install or vice versa.