[seningen]

This is a little far fetched.....

There is a very small pin that is the far end of the chain guide post.
that the chain guide rests and rotates on.

If that pin sheared off, the end of that post could be "floating"
and when the chain is stressed it's vibrating against the inner wall of the
chain guide chamber?

I broke one upon reassembly one time when I was torqueing the chain guide post.

Mike