I have a Kenmore dishwasher model 363-14772100. About a month ago I noticed it was not cleaning as well. I would put the dishwashing packs of detergent in there and it wouldn't even dissolve all of the pack or even all of the liquid detergent inside. It has seemed to get even worse since. I have just regular liquid detergent now but even if I put in just a little bit and have the dishes completely rinsed of all food before washing, it doesn't clean. It leaves detergent residue on the dishes and just does not clean any food off. There is no leaking that I'm aware of. The spray arms seem to be clean. It sounds like it's running all the cycles as usual. I know it is still heating the water. What else could be the problem?

Thanks,