I wondered if the cylinder stop was there. Be careful not to bend it too much, as it breaks easily. I broke one trying to make it work properly on my 22r model.
If the sear and spring are found, they can be a bit tricky to put in and I can see why someone who disassembled it might have left it out. The sear fits into the trigger guard well with the 'V' shaped spring against the trigger guard and the pin needs to go through the trigger guard and the sear to assemble properly. I put the sear inside the trigger guard, then put a round toothpick that fits through the trigger guard and the sear. Cut off the toothpick on both sides so it fits smooth to the trigger guard. Then assemble the trigger guard and put in the front pin, making sure the trigger return spring is in properly, then the rear pin. The rear pin will knock the toothpick out the other side of the trigger guard.