filter not working after blackout

Help please at some point while I was at work I suffered a power outage now I don't think the power was out long but hob filters on 2 of my tanks did not start up properly. The smaller tanks and the sponge in my 75 restarted by them selves when the power came back. The penguin 350 on my 75 and the hob on my 20 I got restarted alright when I got home. I can not seem to get the emperor 400 started again. It makes an awful grinding noise and can't seem to pump water properly.

I have taken it apart, removed gunk reassembled primed it and it still won't run for more than a few minutes I even raised the water level.

Any suggestions to include details please this filter came with the tank so I have no instructions

so far my fish are all still swimming

thanks

Actually It wasn't that gunky I am a little worried the moter burnt out the alarm clock upstairs was blinking 6:00 when I got home meaning the thing had been dry running for at lest six hours

thanks You two were right something was mucking the impeller up or maybe I did not put it back together right the first time any way it is working now