A reprint 1913 catalog is available here. This catalog has good cross section illustrations, descriptions & also a basic disassembly procedure. Don't recall for sure if it actually covers the top lever or not but will at least get you close to it & the rest should be obvious. You can try some of the used gun parts dealers such as Gunparts Inc for the spring. Seems that Brownells used to sell a assorted lot of V springs which could be adapted to many purposes, not sure if they are still cataloged or not.
