The first thing I would do is post a wanted ad here on RCU as well as every other RC message forum you can find. Once you have those posted, head over to NSRCA.org and see if you can post the same message there. There are bound to be parts sitting in some old pattern fliers garage somewhere. I have one diaphragm and plunger that I'm hoarding for future use in either my side or rear YS 60. I picked them up in an LHS's obsolete engine parts box, which, is another place to look. If a swap shop comes through near you, check it out. You never know what you'll turn up at a place like that.

Good luck.

John