Reviving and maintaining old (and new) tuning machines
Lubricating guitar tuners - StewMac
Maintain Open Gear Tuning Machine - YouTube
Reviving and maintaining old (and new) tuning machines
How to Keep Acoustic Guitar Tuners Moving Smoothly | Acoustic Guitar
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Tune Up Your Gears
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Liquid Bearings, the TOP QUALITY 100%-synthetic oil for guitars, it makes the tuning keys turn smoother, which makes for easier guitar tuning and helps them stay in tune longer! : Musical Instruments - Amazon.com
How to clean and lube dirty old guitar tuners - StewMac