Skimmer crapped out....where to start troubleshooting

[gregzz4]

Good advice and is where I'd start
Pull the pump, or at least the impeller, inspect for damage/wear/magnetic coating swelling etc
Some of the older impellers were poor quality and were coated with plastic. The metal would swell while rotting and cause big issues
Also, your impeller housing could be getting a buildup of calcium
So, try your best to pull the pump and clean stuff out

Could be you get lucky and find something simple, but whatever it is you'll most likely see something amiss