Sounds like the valve o-ring.
Simple fix.
I recently obtained a second hand Daisy 717 that was working but started to get resistance to the cocking lever when it was about 3" away from the cylinder, not the 1 1/2" specified in the manual. Another strange thing was if you part pumped the lever (just closing it half way then pump again) the closing resistance increased. As a result I decided to strip it down (using the guides that are available), clean the parts & relube, now it dosen't hold air. As you close the pump lever air can be heard leaking out around the breech area even with the action cocked, there is also some resistance when opening the lever. If the action is not cocked & the lever pumped air can be heard going through the barrel on both opening & closing strokes. Can anyone suggest what the problem may be.
Thanks
Greg
Sounds like the valve o-ring.
Simple fix.
Zastava Owners Club.
It's a while since I had a Daisy 717, but going from memory, is there any chance you've got the end of the cocking arm located wrong relative to the valve stem and so holding the valve open?
This is the stripdown guide I used :- http://www.pilkguns.com/tenp/spd747.htm
Walther CP-2 Match, FAS 604 & Tau 7 target pistols, Smith & Wesson 6" & 4" co2 pistol, Crosman 1377,
Baikal IZH 53 pistol, Gamo CFX Royal,177, Umarex SA-10 CO2 pistol.
Did you get it fixed?