Quote Originally Posted by --ped-- View Post
an easy way to rough set the piston so it cams over is to get a bit of 1/2" dowell or rod and in sert it down the compression tube till it hits the valve
then mark the rod through the lever pivot pin hole
once removed fit the piston to the rod line the pivot pin hole up on the rod and lever and adjust the piston till it's flush with the end of the rod or a mm longer to allow for wear in the linkages
tis will give you a starting point
another tip is to use a 3/16" punch in place of the roll pin
the spring steel in the lever is designed to keep the lever up with no air pressure and was later swapped to a plastic button in the lever that used friction between the two parts of the lever
Sheridan and Benjamin kept using the spring steel in the lever as they stopped using an adjustable piston rod in the early 60's(sheridans not sure on date for when Benjamin did)
Hi ped, thank you for this excellent advice.
Very useful.
I will do this.
I'll wait for my pump rod from JG Airguns to arrive first.
It's still strange that I didn't feel the pump cup hitting the valve when I adjusted the pump rod to maximum length. Or I missed it.
We'll see.
I do believe that the fact that my pump arm drops down when there is no pressure in the valve, is caused by a worn spring steel in the lever.
So further pump rod adjustments will be aimed at getting more efficiency (power).

@junglie, thank you. In the case of this 107, I would not like to store it with air in the valve, because the hammerspring needs to be tensioned (the gun cocked) to do so.
In the uncocked state, the hammer presses against the exhaust valve, and air simply escapes through the barrel when pumping.
I think the best way to maintain guns like the 107 and 108, is to shoot them regularly.
On the other hand, as 45flint pointed out earlier, a reason for this 107's relatively good survival might be the fact that it didn't work!