For many household items, screws should be tightened if they seem loose. But for woodwind instruments it’s a little more complicated.

Woodwind instruments (flutes, oboes, clarinets, bassoons, and saxophones) have many screws on them. They are usually the slotted type, for which you would use a standard (“flat-head”) screwdriver. And some of them need to be tightened when they become loose, but some should be left alone—and it’s not always easy to tell which is which. If you aren’t sure, take it to your teacher or a professional instrument repair shop.

When tightening screws, always use a screwdriver that fits the screw very closely, to reduce the chances of damaging the screw. Mismatched screwdrivers can also slip, causing injury to you or scratches on the instrument’s finish.

Here are some kinds of screws you might find on your instrument:

Some screws simply hold some non-moving pieces together. For example, these screws on a saxophone hold this key guard onto the instrument. It’s not a moving part; the screws are just there so a professional can remove the key guard to do specialized work on the key. If these screws are loose, you can carefully tighten them just until they are snug.

The same is true of these screws that hold the oboe’s thumb rest in place—they are part of a non-moving assembly. If they won’t stay in place, the wood may be damaged (the hole is “stripped”). A good repair shop can fix it for you.

Woodwind instruments have many pivot screws, and also pivot rods that have slotted ends like screws. These allow some of the instrument’s keys to pivot (rotate) a little when you press and release them.

Here is one of the pivot screws on a flute. The threaded part screws into a post that is attached to the instrument, and the pointy tip of the screw fits into a void in the end of the key, holding it in place but allowing it to pivot smoothly. For a well-made and well-maintained instrument, usually you can screw these in all the way until they are snug and the head of the screw fits into the post without protruding. But if that makes the key stick or misbehave, it may be necessary to loosen it just slightly.

Here is a flute pivot rod. When it is screwed in it looks the same as a pivot screw, but when it is removed you can see that it’s long enough to pass all the way through a post and the keys’ hinge tube, and then screw into another post. Like a pivot screw, a pivot rod can usually be screwed in until snug, unless that seems to cause a problem.

Most of the woodwinds also have at least a few adjustment screws. These allow a professional to fine-tune how some of the keys move. They need to be tightened a certain amount, no tighter and no looser, like turning the knob on an oven to get the right temperature. If it’s too loose or too tight, it will make the instrument difficult or impossible to play. Making these adjustments properly requires specialized skills.

Here are some of the many adjustment screws on an oboe:

And here is one of the few on a clarinet:

If you tighten these adjustment screws and don’t know what you are doing, you will probably need to take the instrument to your teacher or a repair shop to undo the damage. This can be time-consuming and expensive.

If you have screws that keep loosening on their own, this may be because they are dirty, damaged, or need lubrication. A good repair shop can clean and repair the screws or rods without damaging them (or replace them if necessary), and can determine and apply the appropriate lubricant. (Most household oils aren’t right for the job.) If the screws continue to loosen after this treatment, take the instrument to the shop again and they may use additional methods to secure the screws in place.