I am looking to buy a used trombone, from Craigslist or similar. I'd prefer not to spend much more than $200 on it. I want to learn to play the trombone, but I know absolutely nothing about the instrument. When I meet with a seller and have the chance to examine the trombone, what should I look for? What are the parts that are likely to be damaged or faulty that would drive down the price of a used instrument? What are some qualities a 'good' trombone might have? What tests or trials should I run on it to ensure that it's working properly (or as properly as possible for the price)?
Its definitely tough to evaluate a beginner trombone when you've not played before. I would try to find someone who has at least played for awhile to help you evaluate potential instruments. A good high school trombone player should have enough chops and an ear to tell you that one is better than another, and suitable for beginning. You don't want very inaccurate partial slotting, stuffy tone or extremely poor response.
In terms of condition, you absolutely don't want any dents or bends in the slide section. It should move fairly freely. If the slide grates significantly, or has a much rougher patch, it means that there is a dent, or the alignment is very out of whack. A repair could run anywhere from $20 to $100, so just be aware of that. Realize that you have to move your slide to change notes, and make sure it slides easily enough for that. (Note if the trombone is very old and dirty, some of the sluggishness could be cleaned off with a good cleaning, so keep that in mind as well. A trombone player would probably be able to tell you how bad the slide really is.)
I would not overly focus on cosmetic defects as long as there are no major dents. Try to stay away from un-branded instruments; they're not worth the money in 95% of cases.
Keep an eye out for the following brands; in general they signify a certain level of quality, repairability and playability, as well as resale when you graduate to a more advanced/different instrument.
King (H.N. White) Yamaha Olds Conn
These are all high-quality brands, but you can definitely find some reasonably priced vintage models that will play well. I've also had mixed luck with Jupiter and Holton student models; try to get someone who plays to play one for you and give their input.
Keep an eye on craigslist, or talk to some high school players that might be getting rid of their student horns in favor of a more advanced one to continue on. The trombone.org/classifieds usually contains higher-end professional instruments, but it's definitely worth taking a look. Updates occur on Mondays.
A mouthpiece can be convenient, but don't rule out a good horn because it doesn't include one!
Other than that, once you've gotten past a certain skill level be ready to resell it, and get something a little nicer/more advanced so that your interest will continue!
Welcome to the party!
I can think of a few:
Not so easy,
(more suggestions welcome)
Check if the handslide is closed and does not leak. Do this by demounting the trumbone and pressing your thumbs on the two notches and then lifting the handslide by just holding it at the grip.
Good luck. Welcome to the tromboners world!