dolmar/makita 64xx/79xx stupid rich and no longer runs correctly after 3 years

[logicallycompromised]

hello good sirs and misses,
this saw has been bullet proof over the last 3+ years with minimal carburetor adjustments throughout the season.  about 5 months back i helped a friend drop a 9" hickory tree leaning over his house.  the saw started minto pinto like every other time in the last 3 years.  i set the ropes as the saw warmed up and made my notch than tuned the saw off for a teaching moment.  well the saw has not run correctly since.  couple of things i noticed upon pulling the carburetor apart. the reinforced looking semi transparent diaphragm was stretched out so i ordered carburetor kit to replace it.  i just installed the new kit and found it odd there was no welch plug observed.  i had previously never taken the carburetor apart outside of about 1 week ago and am pretty sure i did not observe it then either nor could it have been misplaced.  i just pressed the one the kit provided into place with excitement to have the ol girl back and was disappointed again.  the closest i can get to running is with the low side all the way bottomed out and the choke idle throttle adjustment being used with choke pushed all the way in(provide slightly open throttle without choke plate activated).  i can not get the saw to cough without the aforementioned combination and when it does run it sounds absolutely terrible.  during starting it will pith fuel out of compression release, muffler and intake.

what could be causing this rich condition?  do welch plugs dissolve(seemed to be aluminum but trying to explain where mine could have gone)?  i think the carburetor needs them maybe i need to try and seal where the welch plug was pressed in better.  seems that is the likely suspect as of now, i think without the welch plug there or sealing correctly the venturi created in carburetor will draw in extra fuel as the saw runs, no?

please help get the ol girl and i back on good terms.  thank you for your time!

[Allar]

Pull the muffler and take a look at piston.

[ehp]

Something is screwed up, welch plug just do not disappear ever so some how or way if it gone it had help doing that, have seen very few like 2 or 3 welch plugs that fell out but the welch plug would still be in carb just not in the proper hole and those were because someone rebuilt the carb and did not put welch plug back in proper . I would think you need to get carb rebuilt properly . Gas pouring threw motor sounds like the needle in the needle and seat is not set correctly or maybe the spring is broken that sits under the needle and seat arm or got crap on needle where it cannot seat proper and regulate the fuel flow