You don't use an allen key. To up the pressure, you need to use the small plastic disk you got with it (or a 10p if you don't have one) and screw in (or out, I can't remember off hand which) the front of the lpr (under the barrel). This will up the pressure inside the marker and force the ram and bolt back to where they should be.Lol never worked since i got it, ill try uping the pressure will get the allan keys out in a min, i didnt get spares apart from like 2 orings, 2 like fat silicon orings, a tank oring it looks like, a plastic circle and 1 ball detent, I rember it was 0-10 i think that was on the manual but ill check in a min,
Cheers