The spray arm on every dishwasher is loose except for Bosche, the water pressure holds it up and firmly seats it on a split washer.
A chugga chugga noise usually is asociated with no, or little, water in the dishwasher.
Try a new cycle and see if it fills up to the bottom of the Heater, if not , you may need a new water inlet valve.
Hope that helps!
If you feel my answer was satisfactory please click on the green "ACCEPT" Icon, the question will not close, and you may follow up if needed. Thats the only way I get paid for my advice.
Feedback is always appreciated!