Yeah sometimes the o ring on the needle will get flat or dry/crack allowing
air to seep in. A new O ring perhaps.

Check to see if it's just that little tab thing that's bent out a little that
dosen't give a tight or click field on the needle.

The next time you go out to the field, notice some people
have fuel tubbing over the needle to try to sholve this problem or prevent
the needle from rotating during flight.

You might try richening the highend a little at a time first.
With the nose pionted up, have a couple of guy hold the plane. I guess.
and check the transition.

Perhapes your engine is doing this ? Splutter as you're taking off.
It's from the oil build up in the muffler from idling which must be cleared out.
This why I give myself plenty room for take off.

Once the plane is in the air , It'll run fine if it's on full throttle or close to it.
The engine doen't over heat or die, if you choose to run a full tank.
But it transition like crap.
I leaned the low end a little bit at a time to dial her in.

If you can't get it to full throttle without the engine wanting to die.
The high end is too lean. Give it more fuel, but by doing so
you must retune the low end to give a better transition.