The regulator on my kegerator isn't adjusting anymore. I noticed the pressure seemed a little low, so I tried to boost it up a bit; moving the screw in or out didn't move the gauge at all.
What are some troubleshooting steps I can try? Or do I need to replace it or have it rebuilt?
Pressure regulators are really pretty simple to take apart and diagnose. Likely you had beer flow into it, and now its gummed up. Unlikely that you pierced or broke your diaphram.
Are you hooked to a keg when you are adjusting the pressure? Being hooked to a keg will effect the displayed pressure. Probably not your problem but thought I'd mention it.
most welding supply stores offer replacements and might be able to rebuild them.
Diaphrams go out all the time