I finally landed one of these. Now I have a question. It is in an older model serial #10438644 I have not checked the schneider web site yet for info on this model. It is in a Linhof Shutter that has, for some reason two different retainer rings in two different sizes. Why? I do not see how the smaller could be used or what it would be for. The shutter needs over hauling, who could I send it to that would be fast? Has anyone used Tempe Camera in the Phoenix area?