I wanted to buy a pedal steel guitar, and they are humungous amounts of money, and scarce second hand, so the advice I got was wait until you see one on ebay being sold cheap because it goes out of tune, and the owner cannot fix it, and snatch it up for a song. Remove the changer and clean out all the WD-40 they lubricated it with, and replace it with silicone spray. WD-40 apparently always gets used, and lasts about three months and then starts to get sticky and the dust, which is the cause, just wrecks them. I waited and eventually found one with the declared fault. Cleaned it all off, re-lubricated with the correct stuff and it's been perfect. The solvent in WD-40 evaporates, but the lubricant doesn't.