If its similar to the Glock 23 there is a slot in the frame that you have to insert it in. I use tweezers to guide it in the slot then push it down with the Glock tool. You can download manuals or even better go to YouTube and they usually have detailed videos on just about anything. There are quite a few videos on YouTube disassembling and assembling many different Glocks. Hope this information was of use to you.
Went utube and actually didnt find anything with installing/reinstalling the lever spring but then i got some tweezers and seen a few pics online and got it back in . Thanks for ur reply. With tweezers it worked so much better lol.
This thread can now be closed/deleted. Thanks again.