My Mp20 which has been running fine for about a month, now makes noise. Of course this is after I had it on pause, accidentally unplugged it, trying to find the filter plug, and then plugged it back in causing it to turn on partly submerged. It makes a really bad grinding sound once its fully revved up and adjusting it doesn't seem to help. I think it might be the propeller? Is there away to adjust it? Thanks