Could be the pressure switch thinks it still has water in the machine so does not refill. Power off r/h/side panel off. Should see towards the front of the d/w a black pressure switch with 3 oe4 thin wires and a pipe that goes to the sump. remove the pipe off the p/swt, have a cup of luke warm water in the old gob and blow this water through the pipe, reconnect and see if anything improves. Can also be poor filling via l/h/side fill matrix as the air break gets limed up at the top where the elongated C shape is moulded into the matrix.