The Floating Points Lobes Mystery

Upon checking the points gap one day, I ran the engine with the cover off "just to see". 
What I saw was not what I was expecting - the lobe that the points ride on was drifting in and out -
on an axis with the camshaft.  Here is a video of it's motion.  It appears to float a couple of millimeters at least,
which is way beyond spec...


For illustration, I managed to dig out a spare of the part that includes the lobe - here it is, below.
It is item 7 on page 3-10 of the sedan parts manual (I have a sedan engine in my Coupe)
as the "mechanical spark advancer assembly"
The lobes have some pitting so I doubt it would make a good replacement, if needed.

Below is the same part shown sitting on the (passenger) end of the camshaft. 
A washer covers the end and a bolt holds everything together (not shown)




The camshaft is held in place securely by the camshaft holders at either end, shown below.

Left side
Measured to be half a millimenter


 Right side
No slack at all


SO THEN, it appears that there's almost zero "wiggle room"
for the camshaft - and the lobes - to float. 
How and why is it happening?