Umarex NOTOS accuracy issues.

So it looks like cleaning the barrel was what I needed. I got the patchworm kit and ran a couple pre soaked patches through and then several dry patches. Dry fired it a few times to blow some air through and it started grouping like normal again. I had a tin of Crossman Premier pellets and they seemed to group a little better today so I dialed it in with those. One house sparrow made the mistake of landing on my martin house and never knew what hit him.
 
So I noticed something else. I had it sited in and shooting good. I went out last evening and shot a few pellets and the accuracy was falling off again, not as bad though. After about the third shot I felt something on my finger at the trigger. Looked down and the allen screw (which I think adjust the trigger pull) had somehow backed almost all the way out. I ran it back in and fired several more rounds and it was back shooting straight again. I was able to drop 2 house sparrows this morning so that is a good thing.