Usually you can at least get your fingers or a wire hook in via the pump basket housing. I agree with Chris that this is too coincidental with vacuuming. The clearances between the impeller and the pump housing aren't much and something small could have gotten caught. Something else to try, remove the basket lid and drain the water from the basket chamber so the pump is dry. Turn it on for a few seconds and listen to see if the noise is coming from the impeller area. Won't damage anything to run dry for even a minute or so. If it is something caught I would think the noise would be quite loud listening at the basket with no water in the pump.
Just a warning...be sure the pump can't accidentally come on when you're messing in the impeller area.
Al