Hello, Thank you for using this service, I will be helping you with your problem today
good morning, The issue is the drain pump not the circulation pump. the drain pump comes on in certain parts of the cycle (thus the intermittent noise) the impeller on these pump get loose on the motor shaft and eventually the pump will fail to drain the machine. you need to order and replace the pump. heres a link. http://www.repairclinic.com/PartDetail/Drain-Pump/154580301/1257094?modelNumber=PLD2855RFC1?RCAID=1000065 just click that blue link to order it. this is located near the back right side and the machine has to come out from under the counter to replace. its not that difficult once the machine is out, thanks and best wishes, Bryan
On these machines the upper and ;lower spray arms run independently from each other. in other words the lower spray arm will run for a few minutes and the it will switch to the upper spray assembly and back and forth is how these run. check the spray arms and the tubbing running up to the top ones, you may have something in those thats causing the noise then.