A small amount may be left on purpose, some keep the seals wet and from drying out, if having issues, I use a carpet cleaner to suck wAter out, when doing this, suck the sump area too, you may get lucky and pull or vacuum the debris up, that was my problem, it's been fine for two years

People, remember to "prime" your system with hot water at the SINK before doing this, these heaters are only so strong, my suggestion is, and manufacturers also, is to run sink until your water is hot, then run the dishwasher.

This is likely due to scaling building up on the rotator thus making it out of balance, as it rotates around it "grabs" and this is what your hearing.

If water is left standing in your machine, there is a couple things to immediately do, first I went and got out my carpet cleaner, took attachment off the hand wand, and sucked the water out. (You may have to empty it once or twice before you have all the water out) while vacuuming water out I took the filters off and vacuumed the pump recess area, now I had a dry dishwasher in which to work on. This vacuuming actually would fix it for a while and I would find small debris of what I think is scaling, hard water deposits, and unit would run for another month or two then clog again. The last time I did this I then used a tool and pryed around and found a large peice of debris that was slowing down the process to the point of either leaving a little water, or blocking with other debris. Now it's fixed. My advice though is to use a wet vac, or even carpet vac, to empty to the pump, and even vacuum the pump area, you may get lucky if it's debris, but at least you'll be able to see what is going on.