Do not know where you can obtain diagram, but from personal experience suspect the only spring which popped out is the one for the rear trigger. This simply fits back onto a small spigot inside the top of the lever and into a slot in the outer case. In order for the switch and brake mechanism to operate be sure the loose plate on the switch operating rod is placed between the two white prongs on the front lever and inside the rear lever. When correctlly fitted this plate should be more or less horizontal with both ends hidden inside the levers. Hope this helps.
JB Glos, July 2011