I was given a Daisy 131 airgun .I took it apart to refinish the stock and clean and regrease. I got it all apart, cleaned and regreased but didn't take a picture or two beforehand and now I am having trouble getting it back together. I got the spring and piston in the tube but not sure how to get the trigger housing fitted. In addition, I lost a tiny coil spring. Didn't know where it went anyway. Can anyone help?