[LeakProof]

I agree, that's a piston c-clip. Those buggers are really tough to get out, I could see, how one could easily end up in the case. One of my clips, ended up across the garage.

When I changed all my chain ramp's out, I had several broken pieces, end up, in my sump, that looked just like that.

I stuck my hand in the sump, and retrieved every one, that I could account for breaking.

The old ramps were pretty brittle.

The new one's, I removed recently, did not break like that upon removal.

Leakproof.