Had a GE washer that was flooding due to a lot of sediment in the tub blocking the water level switch plastic hose. Just dumped a lot of vinegar in the tub, let it sit for a while, and blew a mouth full of water in the plastic tubing to circulate the stuff in the bottom, sure enough, it worked and cleared everything out! It now works fine.
This worked as the sediment was from cheap laundry detergent and the vinegar dissolved the stuff.
May not work for calcium or well water iron sulphides. CLR may work for this.