What is OSEA?

OASE rather.

I was not familiar with OASE pumps but one I chose at random seemed very nice and must have been a mag drive pump since wattage was very low (if honest value). The rotor on these just pull out, probably with part of the outer housing or bearing. It would certainly be worth taking it apart. For one thing, you could simply have a bunch of vines tangled up in there. I usually clean mine out once a year or so. The vines will stop motion, but at least in my case, that didn't damage the pump.

I pulled the pump, and will unscrew the main housing to see if the rotor is just frozen. Pump was hot when I found it not running yesterday. Will update if anything develops. Thanks for your help everyone! If needed, any recommendations for a new pump/filter for my 6'x8'x2' pond with about 5 feet of waterfalls? No plants due to shade and raccoons. 1 large koi, and 6 comets. It runs year round.

Unscrewed the housing of the pump, and the rotor was stuck. I managed to loosen it up a bit, but it still has a tight spot. Tried it out anyway, and no luck. I think it's time for a new pump/filter. 14 years is a pretty good run! I don't think this model is made anymore, so I'll have to try to figure out something similar, or reconfigure my setup.