TromboneChat

I play a Getzen Eterna II trombone, and it is so sharp that to tune properly, I have to pull the tuning slides out as far as possible. Even then, I have to compensate by extending the positions. Is there a solution?
ChatGPT suggested: 1) check F rotor position (doubt this is an issue as it plays fine), 2) modify with a longer lead pipe or tuning slide (not optimal), or 3) try a mouthpieve with a deeper cup (currently playing a 6 1/2 AL-L).
Thanks, Steve

Only thing I would think of is to also check the insertion depth of the mouthpiece. I briefly had the same model and had a similar issue.

Getzen trombones are built short. One thing you might do to help mitigate this (if you aren't already) is to tune with the hand slide out about an inch or so from the bumpers. This should mean your tuning slide won't be pulled so far. (This is a good habit to do anyway.)

Have a tech check to see if there are any leaks, like a leaky spit valve cork, bad solder joints, etc. These can wreck havoc on pitch and intonation.

If all is sound, then try a mouthpiece with a deeper cup (like a 5G or 51), which Getzen trombones seem to like. A 6½AL is also a little shallow/small for many people on large bore.

If none of the above helps, and if you're unwilling to modify it, sell it and move on.

Just put in a spring.