A customer sent me a Columbia rear mount tonearm with a reproducer cast right on the end of the arm. It is a one piece unit painted black with gold strip on the arm. At first it looks very much like the usual Columbia rear mount arm with flat back Analyzing reproducer screwed on, but it is not. The problem is this unit is missing some type of retaining ring that would hold the metal diaphragm and gaskets in place. The needle bar and diaphragm are both attached, but no gaskets or a way to retain gaskets. Can any body tell me what is missing and maybe have that part available for sale? Thank you, Great Lakes Antique Phonographs George Vollema www.victroladoctor.com