I just scored a very nice (if not NIB, then very close) Astatic chrome 10-DA mic head complete with box and paperwork included. For some reason, the retaining ring that secures it to the end of the mic stand doesnt stay attached to the connector on the head, like some dimples are missing. If you plug it in, and screw the ring down tight, the mic head will come right back out and leave the ring behind. Any idea on how to fix this?