There is a diapram and a spring and a couple o rings. Usually an o ring is old and cracked or the diaphram has a hole. I took about 5-6 apart and all of them it was just a old cracked or hardened I ring that was leaking. I have a huge o ring assortment , so I was able to fix all of them without buying additional parts. I would say of it's leaking it doesn't need to get cleaned, there is something that probably needs replacing. I'm not sure if all regulators have them but the only part that needed cleaning was the co2 screen/filter. It was just a super fine mesh screen that stopped particles from entering the regulator, it was inside the regulator. They were all quite dirty.