Push Rods Question - what are the disc things?

[graham-xrfx]

The rods come from a Douglas T35 stationary engine.
Everything in it looks like bike T35 except for the shape of the crankcase. When I started on it, I was taking over something someone else had been at before, partly disassembled. . Condition was unknown - certainly not running. One broken oil control ring, and a list of other problems now fixed.

The push-rods have little steel discs pushed onto them, and I have no idea why they are there, nor what they do.
One of them is clearly in trouble, as it is now loose on the rod.
Looking close at the 4 rocker seats, 3 of them are shiny, and one looks matt.
I am guessing that at some stage, the rod was not seated (hard to imagine)!

These discs are a mystery to me. Were they to dampen vibration, or something?

For me, one question is, which way up do they go?

The disassembly procedure in the manual suggests  the "disc" ends might go down near the cam follower, because it says to "take out the push rods when the head is off" , and "there is no need to remove the rockers unless there are signs of excessive wear in the bearings".

Were the disc ends to be installed near the rockers end, then they are in a place trapped by the rockers assembly, which would have to be removed first.

If anyone knows what these might be, and can help in any way in resolving my uncertainties, it would be greatly appreciated

Thanks if you can help.