I have inherited a Bosch dishwasher model SMS6032GB/14 which I understand to be about 10 years old. It cleans stuff on the bottom rack very well, but sometime the cups etc on the top rack come out with specks of muck baked onto them. It will do this for a few washes then revert back to working fine again for a while before doing it again.
I suspected a problem with the upper spray arm so when it started misbehaving I opened the door several times during the wash and noticed that the arm wasn’t moving. I took it apart and checked for blockages, but all seemed OK. There is one loose part in the spray arm (a coned shape bit of clear plastic) – it sits in the bottom of the tube and I assumed is designed to direct the flow of water along the arms. However it was sitting what appeared to be upside down (like an upside down unbrella). I tried turning it over and the dishwasher worked fine again for a while.
It then reverted back to its old ways. I took the arm apart again and noticed that the cone was again upside down. I realised that there was nothing to stop it turning around itself within the spray arm. Am I barking up the wrong tree here? or is there something missing from within the spray arm which holds the cone in place?
Many thanks for any help