I’m a trombone newbie with some trumpet & cornet experience who recently picked up a 1950 Buescher 400 T-bone. With valve instruments there are a variety of ways to assess compression & valve condition, but as a trombone beginner I wasn’t sure how to tell for if what I was holding was junk or not, especially at first when my chops were weak. It was in seemingly good shape when I picked it up: slide worked smoothly, no spots where it’s worn through; only minor dings; tuning slide wasn’t stuck. Things have gotten a lot better as my embouchure strengthened, so I’m pretty confident now that this horn at least isn’t a beater, but other than obvious plating wear / damage to slides, how do you tell when it’s worn out & needs replacement or repair?

The way to tell that something needs replacement or repair is that something either works badly or doesn't work at all.

Dents, plating loss on the inner tubes, visible misalignment when putting outer slide on inner slide, it just being slow, or the dreaded red rot. All mean that the slide should be taken to a tech. There is almost no magic to trombone slides. If it works well, you can't fix it. If it works badly, you can fix it.

It is rare that a seal on a slide is actually bad due to the tolerances being bad, but the cork can be an obvious issue. If you take the slide off, put a mouthpiece in and cover the other hole and air leaks, that's a sign that the waterkey cork needs replacement.

It's actually pretty hard to wear out a trombone slide. As long as it's moving freely and not making noise, it's probably OK. Lots of slides still work fine even once the plating starts to wear through.

Thanks for the replies. I think as a newbie I generally overestimated the fragility of the mechanism. Also I only paid about $50.00 for the horn so I was prepared for it to be junk, and it was the first trombone I had tried to play so I had no frame of reference.

[quote="Peacemate"]The way to tell that something needs replacement or repair is that something either works badly or doesn't work at all.

Dents, plating loss on the inner tubes, visible misalignment when putting outer slide on inner slide, it just being slow, or the dreaded red rot. All mean that the slide should be taken to a tech. There is almost no magic to trombone slides. If it works well, you can't fix it. If it works badly, you can fix it.

It is rare that a seal on a slide is actually bad due to the tolerances being bad, but the cork can be an obvious issue. If you take the slide off, put a mouthpiece in and cover the other hole and air leaks, that's a sign that the waterkey cork needs replacement.[/quote]

How common is real red-rot in trombones? I’ve seen it on a lot of old trumpets & cornets, usually in the lead pipe.

Red rot usually shows in the slide crooks. Rarely affects the tubes. It is usually due to moisture left in the instrument coupled with a corrosive atmosphere.