You need to remove at least the one valve that is not coming back up. You can try cycling the valves with your finger tip, the springs are soft enough that you can push them open easily. The fact that the springs are soft it takes very little to stick them open which is the case with your engine.

There is no need to remove the sprocket from the cam for this work, Just remove the bolts holding the cam caps so you can lift rockers enough to get a thin socket on that jet valve and thread it out of the head. Leave the bolts in the cam caps so the cap are not pushed off the shafts by the springs that position the rockers.

Once it is out you can do what is needed to free it up. most of the time just cycling it will dislodge what is binding it. The spring removes very easily, the keepers are very small and will try to get away from you and hide. Once you slide the valve out and clean up inside the cartridge, put back together and test that it moves freely.
Or just buy the eliminators.

Charlie's right about the cam sprocket, I only take it off to take the leverage of the cam tensioner off the cam.