Echo SRM-210 trimmer won't stay running/move to the "run" position

I put a new carb on it cause I bought it for next to nothing cause it wouldn't start. new carb worked great. I don't use the trimmer that often.



Lately it has been acting up. It will want to stall and or loose power when I pull the throttle near full.



Today it worked fine for a bit but after I shut it off and then tried to start it, it wouldn't stay running. I'd have the choke in the "cold start" position and start it and it would run but would die when I moved the choke towards the "run" position. Even a minute amount of movement from the full choke position and the trimmer dies.



I had seen other threads regarding this trimmer and people suggested cleaning the spark arrestor screen in the muffler. I did that with no improvement.



An observation - the prime bulb doesn't release easily. When I push it in, it draws gas but it slowly pushes out.



I also replaced the fuel kit with a new Echo one: all new lines, etc.



I took the fuel lines off today and tried the primer bulb and it worked without any resistance, but when I hooked the fuel lines up again, it drew fuel into the prime bulb slowly.



Might the fuel filter be gummed up? If so, is there a way to clean it?