Tuning machines are pretty standard. That is not to say they are all the same, but that they fall into several catagories. Take it to a good repair shop that has been in business for a long time (like mine, not that it will do you much good, living in another state and all), and they are likely to have either a used gear or a bunch of new single gears from sets they broke up for other idio....umm, unfortunate guitar players.
If you can't find a single, they are pretty hard to buy, so you are going to have to get a full set. Pretty much no matter what you are going to have a real bitch of a time finding an exact replacement, which is fine as there are better gears out there.
If you DO chose to go with a full set of upgraded gears, may I suggest Gotoh 510s. There is no better gear on the market, and while they are price accordingly, they are not THAT much more expensive, and they really are better.
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