What kind of upgrades are you hoping to find?
Given the issues you're having after disassembly etc. I think you should call Ruger.
They should be able to at least walk you through reassembly and you can ask them all about any upgrades.
Any modification would most likely be the result of a recall, IF there were a needed modification it would probably be listed here: Ruger Safety Announcments.
Edited to add: We still need to know WHICH Ruger P95 you have to give you more accurate info.