Pretty sure the hex wrenches and o-rings are not included with the AirBugs because they are not intended to switch barrels like the Chaser kits. Not sure why you would want to 'upgrade' the trigger as it is a fine trigger as is. Pull the trigger guard and you will see a second adjustment screw. A bit of time adjusting and you can have a very very nice trigger with the factory supplied parts. As for spare parts and diagrams, well there are none for all intents and purposes. The SPA manufactured guns have very little in the way of spare parts. It it NOT like the Crosman co2 guns! These are not the so called 'lego' guns that the Crosman pumpers and co2 guns can be. No real modding will occur with the SPA guns. You do know these are made in China and Diana has little to do with designing them? Diana does NOT manufacture or assemble them. All that said, you can source seals from PA and the o-rings can be found from industrial supply houses as needed. I own a .22 and a .177 AirBug. Both have been problem free. Would buy them again if something happened to them like theft or fire. They are good little pistols.