You CAN get those parts from Cobra. I had two of those CB's and broke both of those round retainers on the back of the handle. CALLING Cobra resulted on a bag of 6 sent to me at my request since I thought I would brake them again. Well, two year later, no more brakeage. Unfortunately, when I sold my Jeep, the CB went with it and I gave the extra retainers to the new owner.
Again, you can get those parts from Cobra. 1-773-889-3087 (taken from the manual). There was no charge for mine. Hope you get the same results.
Mike