Quote Originally Posted by louisvanhovell View Post
Yes this morning I went the "easy way" by using the 108 pump arm as an example.
As this didn't work, I will have to follow your, ped's and DTFletcher's info to find the correct length.
I'll get there in the end...
Setting the pump arm length is one of the simplest task to accomplish with these guns. Not sure why you're trying to make it complicated. There is only one way to set the pump length and that is the factory way, as has already been described; i.e. to the point where the pump arm over toggles (some incorrectly call this camming) and leave it there. There is simply no point in obsessing about the air hole. In my entire career of repairing these guns, I never once came across a problem with the air hole. I never even look at it since there's no reason. After all, what are you going to do about it? Drill another hole? You can't adjust the pump arm length to accommodate, since you end up with a gun that doesn't function properly.

As I've tried to explain, if that hole isn't doing it's job, the gun simply will not pump up. In short: stop worrying about the air hole!

As for the low power, the first thing to check is the pump head washer; if the pump head washer leaks at high pressure then the gun will not fully pump up and the power will be low. Very few other things can cause that. So, I suggest getting a replacement pump head of the original style with a new pump head washer.