Brett,
G'day Eh from Canada. That's a tough one. By your description, the screw you are talking about is the rebound adjuster, located on the bottom shock clevis, the part that connects to the linkages. This screw should definately "click" when you adjust it. Sometimes they get minor deposits in them (inside) and stiffen up after a number of years at the same setting. I've had to exercise (turn back and forth) mine a few times over the years to get the click back. As to your problem, I am not 100% on this but I doubt that there will be too much pressure on the rod (or none at all). I would suggest turning your shock (or your whole bike) upside down. With some fiddling you should be able to get the rod to move or fall back down enough so you can get the adjuster screw back in. With the rod all the way down will have NO rebound hence the pogo stick. Hope this helps. Cam.