The shank is stuck on my DE mouthpiece. I'm hoping there's a cute trick to loosen it up rather than applying brute force. I've dripped a bit of oil in and I've tried (gently) heating the receiving cup. Neither worked.

Posting here so that the answer might be useful to others.

Thx

Gently tapping for a bit on the connection has worked for me.

[quote="Doug Elliott"]Loosening stuck mouthpiece parts:

You need a rawhide or wood mallet and a 9/16" box-end wrench for large shanks, or 1/2” for small shanks.  14mm and 13mm box-end wrenches will also work.

For the rim, one of two methods may work:

Tap around the top surface of the rim - sometimes that's all that's needed to loosen it.  If that doesn't work, hold the mouthpiece in your left hand with the rim facing away from you, and with the mallet hit the right edge of the rim downward with a glancing blow.  That puts force in the unscrewing direction.  Now turn the mouthpiece slightly and hit it again. Keep doing that until it loosens.  You might have to hit it pretty hard.  The wood or rawhide has enough friction to do the job but it won't hurt the plating.  Rubber mallets just bounce, plastic and anything harder can dent it.  Only use wood or rawhide.

For the shank, put the box end wrench on the hex.  Hit the opposite end of the wrench with the mallet, in the correct unscrewing direction. (Normal threads, turn left to loosen)

IMPACT, not brute force, is what works.

A little bit of Teflon tape on the threads will keep it from sticking.  Oil or grease doesn’t really help.
[/quote]

Doug addressed this in an old Trombone Forum post, here: https://www.trombonechat.com/viewtopic.php?t=462

The shank has a section near the threads that is shaped like a hexagonal nut. Get a rubber jar opener, put that on the cup, and put a wrench on the part of the shank that looks like it should accept a wrench (the nut part). Twist slowly and gently in opposite directions.

Use some sort of thick grease (I use chapstick) on the threads next time.

I used a wrench and belt it in place and twisted the cup by hand.

Doug’s advice is where I would go next if I couldn’t do it by hand.

I always use a TheraBand and a wrench.

I'll be at ATW on Friday. I'll bring my TheraBand and charge $5 per loosen. :-D

reposting Doug's instructions. thanks all.

I've had so many questions about this that I decided to post instructions. I attached a PDF with these instruction plus pictures.

Loosening stuck mouthpiece parts:

You need a rawhide or wood mallet and a 9/16" box-end wrench for large shanks, or 1/2" for small shanks. 14mm and 13mm box-end wrenches will also work.

For the rim, one of two methods may work:

Tap around the top surface of the rim - sometimes that's all that's needed to loosen it. If that doesn't work, hold the mouthpiece in your left hand with the rim facing away from you, and with the mallet hit the right edge of the rim downward with a glancing blow. That puts force in the unscrewing direction. Now turn the mouthpiece slightly and hit it again. Keep doing that until it loosens. You might have to hit it pretty hard. The wood or rawhide has enough friction to do the job but it won't hurt the plating. Rubber mallets just bounce, plastic and anything harder can dent it. Only use wood or rawhide.

For the shank, put the box end wrench on the hex. Hit the opposite end of the wrench with the mallet, in the correct unscrewing direction. (Normal threads, turn left to loosen)

IMPACT, not brute force, is what works.

A little bit of Teflon tape on the threads will keep it from sticking. Oil or grease doesn't really help.

Doug's instructions work perfectly.