My guess is you knocked some debris loose from above and down into the impeller area when you were fiddling with things. Just getting a tiny snail shell, piece of tube worm, or grain of sand between the impeller and housing can cause all kinds of terrible grinding/buzzing sounds. It might be as simple as just pulling the impeller out and washing out the housing and impeller in water real fast. If there is harder build up, you will likely need to do what FUNGI suggested.
The pump cleaner sold at the LFS is just citric acid in powder form. You can probably find it on the baking aisle of a grocery store or can get it overnighted by Amazon if you have prime.
Amazon product ASIN B00EYFKM32
I would mix up like a 1/4-1/2 cup of citric acid per gallon of warm (but not hot) water, take the pump apart, and let all the pieces sit in the mixture for 20-30 min. Then pull each piece out and clean it with a tooth brush under running water. Then let everything dry or paper towel it off. Of particular interest to you and most likely where the rattling is from is something getting caught between the impeller and the housing, so be more thorough in those areas and the rest are less important, but run plenty of water over everything to get rid of the citric acid.
I don't think this is what happened in your case, but the next step would be to check if the impeller is going bad. Sometimes if they run too much with debris between the housing and impeller it causes friction that makes the impeller swell. This too can cause weird noise. This could be corrected by replacing the impeller.
The pump cleaner sold at the LFS is just citric acid in powder form. You can probably find it on the baking aisle of a grocery store or can get it overnighted by Amazon if you have prime.
Amazon product ASIN B00EYFKM32
I would mix up like a 1/4-1/2 cup of citric acid per gallon of warm (but not hot) water, take the pump apart, and let all the pieces sit in the mixture for 20-30 min. Then pull each piece out and clean it with a tooth brush under running water. Then let everything dry or paper towel it off. Of particular interest to you and most likely where the rattling is from is something getting caught between the impeller and the housing, so be more thorough in those areas and the rest are less important, but run plenty of water over everything to get rid of the citric acid.
I don't think this is what happened in your case, but the next step would be to check if the impeller is going bad. Sometimes if they run too much with debris between the housing and impeller it causes friction that makes the impeller swell. This too can cause weird noise. This could be corrected by replacing the impeller.
