I have an old 150mm Symmar convertable lens with a Compur shutter, and the aperture tab broke off. If anyone knows of a source for parts like this, or if anyone has a non-working example of a Compur shutter of this age (it probably doesn't even have to be the same size shutter), please let me know. The knob is an integral part of a small pointer that resides over the aperture scale, which is in turn held onto the shutter by means of a small screw. All I'd need is the pointer with the knob, so just the little "arm" that attaches with a small screw. Thanks!