Back in Nov of 2013 I had our Diana-RWS Model 100 repaired/serviced. I shot it a bit back them and it seemed down just a bit on velocity but no big deal. I didn’t shoot it much after that. Recently I took it back out and it is down to maybe 100-150 fps. I am convinced that the seals are fine because after firing when you open the action to cock it, it “kicks” back on the lever like there is still a lot of pressure in there that is not being released on firing. My question, Is there an adjustment screw or something in there where I can turn the air up more? I could not find a drawing of the rifle to see if I could find any adjustment screw. Thanks for reading and for your help.