I've got an Epiphone Les Paul Standard and I'd like to switch the stock tuners out for some Sperzel locking tuners, but I'd rather not pay a tech to do it. Is it tough? Or just unscrewing and replacing? Thanks for the help!

When I upgraded my Squier with the locking ones used on MIA Delux Strats, I had to drill 2 locating holes each because those had 2 pins, whereas the Squier machines only had one each.

Took about half an hour to git-r-done. Not a big deal.

What you want to do might drop right in. If you get them from the right shop they might have the experience to tell you which variety works best (if Sperzel has that many choices).
Imo, its probably the easiest thing you can do for an upgrade usually.

I've porbably done this about a dozen times or so, most of the time its a direct drop in replacement. Sometimes the screw on the back of the headstock might be a little different so check on that. If your guitar has vintage style tuners, they usually have a smaller hole so you may need to drill the holy a little bigger. Out of all the times i've done it, only once was the screw on the back at a different angle. It almost always went just fine.
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I did what you did, not hard you can do it. but you will have to drill a little hole, and you might want to fill in the old holes... but not hard, took me probably about 2 hours...
also, make sure to drill all the extra holes carefully otherwise the tuners might not be orientated properly, doesn't affect function, but might not look great...
It's cake. You can change these out while changing your strings. I put a set of Sperzels on my Squire strat-the tuner hole is the same size, but there was a pin that I had to drill a hole for, wasn't in the same spot as the screw hole. Just press it down to make a mark, and drill a hole in the spot, pop it in, and your are done!-Just remember to make sure you get the order right, if you get the ones with staggered height posts- the short ones go on the far side, eliminating the string trees.
"Life's too short for bad tone"-Rev. Billy Gibbons