From what you're saying, I suspect your tuners might be on their way out, so buy new tuners. Replacement tuners are actually pretty cheap (especially if you're not dead set on ones that look the same), and are usually better quality than the ones the guitar comes with (unless you buy a higher-end guitar that comes with decent Gotohs or something equivalent).

I redid my old Crafter a couple of years ago when one of the cheap crappy tuners that it came with finally died, and the difference in ease of tuning is amazing. Changing tuners is simple enough. Just remove strings, unbolt the old ones, bolt the new ones on, and screw the new ones into the headstock.

If some of the screws on the old ones weren't holding, and the new ones will use the same screw holes, fill the screw holes before you fit the new tuners. Standard wood filler is fine here - no-one will see it. Headstocks are usually mahogany or some similar hardwood, so always drill pilot holes for the screws if you're not using the same screw holes.

Re-reading again, *are* your tuners actually shot, or is it just the fixing onto the headstock? If it's just the screw fixing, then remove them all, fill the screw holes and refit them. Job done.

As for the tuners being loose, what stops the tuners rocking back and forth in their holes is the nut on the top of the tuner. Make sure all of them are tight. The screw is only to stop the tuner spinning round - it's not supposed to resist any sideways pull from the strings.

If the nuts on the top of the tuners has been loose for a long time, the tuners may actually have worn away the sides of the hole that they sit in. Once that's happened, you're *never* going to be able to tune reliably, and the guitar may have some nasty rattles. If you're lucky, you (or a luthier) may be able to pack out the tuners with something to keep them in place. But the only real solution to that is for a luthier (or you) to drill out the tuner holes oversize (drill press required), plug them with some good wood and then redrill them to the required hole size.

Graham.