Brass Instrument Repairs

While most musical instrument mishaps can be prevented with a little care and maintenance, occasionally things happen. Luckily, many minor repairs can be performed very successfully by the school music teacher. In this post I have compiled several useful articles and ‘how-to’ videos that I hope will help any teacher to quickly and easily find good instructions (or a refresher) for most common brass instrument repairs.

Rule #1: Neither student nor ‘handy’ parent should ever try to do any repairs themselves. Teach the student how to keep their instrument well adjusted, and periodically check all screws and other moving parts. Make sure students keep all slides and/or valves well lubricated, and generally treat their instrument carefully.

Rule #2: Don’t try to be a hero. If you are uncomfortable performing any repair, enlist the services of a qualified repair technician.

Vibrations or rattling sounds

  • Tighten all screws (3rd valve slide, lyre holder, water key, etc.) and valve parts (caps, buttons, etc.).
  • Check for loose braces or other soldered joints (these will require a repair technician).


Stuck mouthpiece

  • Do not use pliers. Do not try to twist the mouthpiece out forcefully. Pull out straight using a mouthpiece puller.
  • Instructional video

Dented mouthpiece shank

Water Key (Spit Valve)

Missing or worn-out water key cork and/or spring

  • Symptom: often the cause of an airy sound.
  • Tools: precision screwdrivers, pliers, wire cutter (optional: glue, lighter)
  • Instructional video
  • Optional: How to make your own cork in a pinch


Loosening stuck valve caps, stuck slides and seized valves

  • Tools: Plastic hammer or rawhide mallet; penetrating oil. Do not use pliers.
  • Put a few drops of penetrating oil into the joints and let sit. If necessary, a few very light glancing blows with a plastic/rawhide hammer will help break up any mineral deposits.
  • Instructional videos:

Piston valves misaligned or mixed up

  • Symptoms: the instrument is stuffy, or air won’t pass through at all.
  • Instructional videos:
  • Vertical alignment: replace worn-out felts with proper thickness. Port alignment can be checked with a valve piston/port inspection mirror.
  • Spring tension: If a valve feels ‘soft’ and doesn’t spring back quickly after being released, the spring may be worn out and need to be replaced. It is possible to get a little more life out of a spring by adjusting its tension.

Replacing strings on rotary valves

  • Tools: precision screwdrivers, scissors, 50-lb test fishing line.
  • Instructional video
  • Instructional diagram 1 (includes port alignment diagram)

Rotary valve port alignment

  • Replace worn bumpers (stops) on rotary valves if:
    • valves are noisy because bumpers have hardened; or
    • notch marks inside valve cap are misaligned.
  • Tools: Screwdriver; X-Acto knife or razor (to trim bumper to correct thickness).
  • Instructional video and additional information

Removing rotary valves

  • Rotary valves may need to be disassembled if:
    • they need to be cleaned well, especially if they sound scratchy or gritty; or
    • the valve action is slow and sluggish even when well-oiled; or
    • they need to be realigned, and simply adjusting the bumpers isn’t enough.
  • Instructional videos: part 1 and part 2

Repairs best left for a repair technician

  • Any of the above procedures if having trouble
  • Loosening stubborn stuck slides and seized valves
  • Removing dents
  • Soldering loose joints or braces
  • Trombone slide is misaligned or ‘sprung’

I hope you find this post helpful. If any of the above links are outdated and no longer work, please let me know, and I’ll update them.

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