So no, it is not normal. I have one in my hand that is maybe 6 years old, I can shake it with no noise at all.
It is hard to diagnose without pics. If you don’t have 4 UL-46 then that could be the problem. These apply pressure to the UL5 (I think) plastic blocks that stop the block from wobbling on the bar. But bear in mind the ones under the windage adjustment dial sit deep in the block - so it might be that you can’t see it. Either way these should be tight enough to create a firm fit on the bar but not so tight as to stop the block moving. They can be adjusted without removing the windage dial but you need a Allen wrench with just the right shape head (shorter and more curved as I recall).
The UL39 part does wear an can be easily replaced - although I have never had to personally.
I‘m assuming the UL42,43 and 44 are all there? If you remove them and the sight pin, does it still rattle?
I‘d take it apart bit by bit. When it stops rattling you just removed the problem. You could have something like a broken spring which could cause a buzz but still do the job(ish).
It will be fixable, they are not that complicated
Stretch