If you have a U-Haul nearby, they stock many of the different pin options.
You MUST be on flat ground for this system to raise/lower your top!
Older Alaskans tend to yaw at the rear, meaning the bottom has splayed outwards and that can put a bind on the rear pistons especially in lowering the top. Check to see how the lower door aligns at the top/bottom of the lower section of the Alaskan. If you detect splaying, then you can do as I did and get some shims to evenly close the gap. Use your jacks to raise the rear just a tad and you will probably see that yawing/gap diminish. Insert a shim on each rear corner and drive it in snugly. Now lower the camper down and check to see if you have now aligned the top/bottom of the lower door with the door jam...if you did, great, if not, you need thicker and longer shims! Once you see that alignment is good, try raising and lowering the top again and see if it goes easier. I still have to open the petcock on the pump and pull down a little on the rear on my '76 CO.
Now....Try bleeding the four lines as you would car brakes; starting with the one farthest from the pump. Be sure to keep an eye on the level of fluid in the pump reservoir!
If bleeding does not help and aligning doesn't either, then new O-rings are needed. Buy them from Brian at Alaskan to insure you get the correct dimension ones.