I had a submersable sewer pump that would not run, myers 1/2hp that made a humming sound for a second and off for 8 seconds, the impeller was free and would never get up to speed. I had found the run capaster was bad. Now I replaced the capaster and refilled the unit with new transformer oil and it pumps. The only thing it seems to still surge a little. The outlet pipe water continues to run and their was nothing in the pump. It appears to have a check valve in the pipe after the pump, might something be blocking it ? It still does pump out water at a good rate, might let it go for now and see if it clears up. Or is it normal for this type of pump to surge, I ran it outside the pit without water and it ran smooth.