Hi, does anyone have any pictures of an air arms s400 regulator (tweaky etc)?

I had a look at a strip down guide of an s400 which was made around the same time as mine, however when they took off the cylinder there was a small brass tube thing (about 1" long) where as my brass tube thing (No idea what it is...valve??) is at least double the size of that

Why is mine different?

Also my power is down, 8.5ft/lb. I took it to the gun shop and he said the most he can do is get it to 9.5ft/lb and I need to clear the rubbish from inside it (I think moisture from when it was dipped?) by putting a couple of tins of pellets through, will this sort it? He said another issue is it could be a faulty reg valve or something

I know how to strip it apart but anything technical and i'm lost

Thanks

Ashley