I don't have any personal experience with him, but Micah Bruce in Omaha (actually a bit south in Bellevue) has a good reputation:
https://www.bruceandsons.com/
The only serious option in Lincoln is CGS Music. The guy who runs it does decent repair work:
https://cgsmusic.net/. Mass Street Music is an OK option, though I've had mixed experience with their repair department. Nothing horrible, but they charge top dollar for what is often no better than average work. CGS might be just as good for less money.
Sadly, Mass Street is but a shadow of its former self.