small engine question - Echo trimmer

hey guys, hoping someone here with some knowledge of small engines can help me out. i really like Echo brand equipment - my trimmer, blower, and chainsaw are all Echo. however, i seem to always have issues with the trimmer. i've replaced the carb a couple times now, which seems to help in the short run, but eventually the same thing always starts happening again and follows this pattern:

starts ok on choke, but doesnt want to be switched to "run". will usually sputter and die. i can usually kind of tinker with the switch, going back to choke, adding throttle, going down to like half choke, back and worth for awhile to keep it from dying. but it will still act like it wants to die. sometimes if i can get it to idle a little on half-choke, i'll let it sit for about ten minutes running like that, and it will finally let me switch to Run. sometimes it runs fine after that, sometimes it still acts like it wants to die.

sputters when i tap the head to release more line. for the life of me i cant figure why these two would be related other than just the impact is disrupting something in the engine. no idea.

it seems like it's a fuel supply issue? intake filter in the take looks fine, and is pretty new anyways. not sure what else to check from there.

none of my other Echo stuff has any similar issues. blower starts on like the second pull every time and runs like a bat out of hell within a couple minutes. same for chainsaw.