How do I fix my Maytag Performa PDB2430AWE?

My dishwasher sounds like it is running fine, however water is not coming into it with enough force to cause the propeller to turn or the center arm to lift up to the top rack. It started making a strange noice (like something was loose and rattling around), so I investigated. When I removed the motor guard I found some black plastic that was in pieces. Part of this plastic was still attached to a stainless steel bar, and slid off easily. It looks like this was a part that lifts a lid which allows water to flow into the dishwasher. Water will flow in, but when it is in it does not circulate with force. Also, water backs up into my kitchen sink, and vice versa (from the sink into the dishwasher.