Thank you for the info and image. What I found was the trigger spring was in the screw slot making it look like a rivet.
I adjusted the screw and was able to get the 2nd stage pull down from 12 pounds to about 4 pounds. The screw was almost all the way out!
In the photo I moved the spring off to the left and I could see the screw slot for adjustment.
Where did you find the illustration ( manual ) and does it go into taking the air rifle completely apart?
All I've been able to find was a one page "manual" that shows nothing other than loading the rifle.
The previous owner put enough oil into the spring / compressor assembly that Dieseling is still an issue and I'd like to remove the excessive oil if I can.
View attachment 397270 The arm of the spring was in the screw slot.