Do you know how to fix GH Guitars? I've got like 3 guitars and 4-5 Neck/frets that are collecting dust because they are broken.
I haven't swapped any parts yet, but I can't imagine it being much different from any other game controller. If they start becoming unresponsive, most of the time it's due to a layer of carbon crud coating the contacts on the buttons. The strum bar on GH guitars feel like a microswitch, so after heavy use that part could need replaced. Not sure what kind of mount it uses, but microswitches are generally pretty easy to find.
IIRC (it's been a while since I took one apart), the strum bars on RB controllers is a soft lever switch with foam pads holding the strum in place. Most strumming issues with RB controllers are caused by the foam remaining compressed.
My GH controller intermittently cuts out, so next time I play I'll probably take that to bits to try and find out why. It's most likely a brittle solder joint. Worst case scenario (i.e. the board is fucked), I might see if I can somehow fit the GH-style strum into one of my RB controllers. If the mounting points are different, this might be one of those cases where having a couple of 3D printers might be useful.
I mean, let's face it, the strum on the GH controllers blows the one from the RB guitars out of the water. With a nuke.