I've got a couple guitars with those covered inexpensive turners. They're are guitars I bought new but paid around $60 for so I'm not looking to upgrade with parts that cost as much at the guitar cost. The most recent my Epip LP Jr. the spent 4 years in the box until I got it. The lube I dug off the turners was brown, hard, and flaky. Pulled the covers took them apart and clean the goop off. Lubed the metal to metal parts that rub as I put them back together with Superlube and they operate much better. The other set I did this to are on my beater acoustic I've been playing decades. I leave the covers off because I like the look better.