There was a Yahoo Group for Russia sailplanes, it moved to some other service when Yahoo pulled the plug, I forget where?
I do have the s-tubes, I’ll keep an eye on it. I have the fairing kit but it looks like a headache, I was planning on skipping it. A disc brake sounds perfect, I’ll try to contact the BFSS. I couldn’t find the Yahoo group anymore, I figured this was the place for the latest scoop. Thanks for the help.

PSA, now that Yahoo is shutting down a replacement group started up at https://groups.io/g/ac-4gliders/. All the original files were kept, they are a very nice read for a new AC-4/5 owner.