1990 300 Windshield arm cover removal?

The windshield wiper on my 1990 300 CE has ceased to articulate when it
sweeps the windshield. It was suggested that I may be able to remove the
oval (more-or-less) cover in order to clean/lubricate and repair it.
However, how to remove it is not obvious to me.

With a small mirror I can see small holes on either side of the
underneath of the assembly, but how to release the cover (if possible),
is not apparent.

Any help appreciated.

Thanks,

C.A.
.