If you need to remove the top dome from a PCC2000 system to access the valve, you MAY want to ensure you have a replacement gasket on hand. A gasket costs about 12 bucks.
I just opened mine for the first time in a year or 2 and found the gasket had somehow stretched by at least an inch. It just will not fit back in the groove to allow the dome to be replaced.
I have opened the dome a couple times previously over the last 10 years without changing the gasket. This is the first time the gasket has stretched.
So... I am now in a holding pattern waiting for another gasket to arrive before I can run the cleaner.
If I had known I would have ordered the gasket to be on-site before opening the dome.