Modern Vespa

To whom it may concern: most likely I've found at least one cause of engine knock - cloged oil passage at the crankpin (marked yellow in the diagram). I put flush oil in it and applied preasure with a syringe—no leak through the connecting rod bearing. I'll let it sit there for a couple of days and try to inject brake cleaner. Bearings are fine. Given that the connecting rod did overheat, what caused this knocking sound? An overheated connecting rod makes pre-ignition? Unlikely. Is there a way to remove crankpin cap? If there is one. Service manual says:
"- Make sure that the 2 caps on the crankpin are properly fitted.
- A wrong installation of a cap can seriously affect the bushing lubrication pressure."

Are these are the "caps"? Doesn't seem openable wthought heavy machinery. That small hole on the second photo beneath the shaft leads nowhere, it's just a few millimeters deep drill hole.