C-clips

It sure helps if you have 3 hands when using this method ;-)

Al, W8UT

Incidentally, I've discovered a pretty good way to remove those C rings.
There are several of them on the gear train of a direlict Hammarlund
SP-600 I'm restoring now. Description follows:

Get two pairs of small needlenose pliers. Ideally, these should be the
kind that are somewhat flat on the ends rather than pointy.

Orient the C ring so that each end of the "C" is pointed towards the
bottom (like an inverted U)

Position the first pair of needlenose so that one tip is resting on the
end of the shaft, toward the top, and the other tip is resting on the
left end of the C ring.

Position the second pair of needlenose so that one tip is resting on the
end of the shaft, toward the top, and the other tip is resting on the
right end of the C ring.

Now, carefully apply a gentle squeezing to the handles of both pairs of
needlenose pliers simultaneously, and the C ring will begin to spread.
When it is about halfway off, you can then insert a small screwdriver
and gently pry the C ring the rest of the way off. Be careful not to
score the shaft.

To re-install a C ring you have removed, simply place the spread-open C
ring back on the shaft, and then take a pair of long nose pliers and
squeeze the edges of the ring until it closes as much as it can on the
shaft. Voila!

-Scott