Hello Roger.

There is a ball bearing race in these lenses and this may well be the source
of the rattle.

If you have any of the old breechlock lenses (they have a silver ring around
the body end of the lens) and an old body such as the EF, watch as you press
the lens onto the body. You should see that as the lens seats in the body so
the breechblock rotates and secures the lens to the body itself. You just
need to tighten the breechlock ring to keep the lens tight to the body.

Glad the lenses are working well. I have always understood that these old
lenses were built to a high standard, the inference being that later lenses
were built to lower standards in order to compete with the independent
makes.

Regards,  Ian.

I own six FD bayonet mount lenses... none rattle.
The one zoom in my bag is 35-105 f3.5 two touch. It has no rattle.
Glad yours are still working fine.

Cheers,

RP©