Mr. Google brought me here because I have a PC 333 sander with 1 broken and 1 missing o-ring part #897558 for the dust collection adapter. Bought it used at a flea market about 8 years ago and never used it except to turn it on when I got home to see if it worked.
I found it in a box a few days ago and took it out of the box. In the bottom was a broken o-ring which I assumed was for the pad. Turned it on the the pad moved, so what is that o-ring for? I thought a first some junk had just fallen into the box and the o-ring had nothing to do with the sander.
Looked at the parts list to see if it called for an o-ring. An o-ring was listed for the adapter. Looked at the adapter and there were 2 empty groves, and the broken o-ring was a perfect fit. The o-rings provide a friction fit so the dust canister doesn't blow off when you turn on the sander. Early models had just 1 o-ring. Mine is a later type 4 that uses 2, because the early models with just 1 were blowing the canister off. So when I bought the sander it was already missing 1 o-ring but like I said, I never used it and did not know. Over the years of storage the second o-ring dry rotted and fell off into the box.
I have some large diameter thin o-rings that were in the bottom of a tool box that I bought years ago. A few were 1/16" thick like the broken one, but the diameter was too large. So the plan was to super glue the o-ring into the grove, cut the excess off, then glue down the cut ends that were now a butt fit. It worked. The friction fit of the 2 o-rings kept the canister from flying off when the sander was turned on. It was such a tight fit that I put some silicone grease on the o-rings to make it easier to slide the canister on.