I'm trying to piggyback an FS-60CB atop my TOA130, but I can't find a way to get it mounted in a way that ensures proper alignment of the OTAs. The 95S tube holder for the TOA130 only has a single threaded bolt on the top. The tube holder for the FS-60 is compatible with it, but there's no way to lock in alignment, and anything I seem to work out looks like a jerry-rigged solution. What is the correct way to mount something onto this tube holder?
Thanks as always for the assistance.