My 2004 Expedition has the same problem however, instead of a screw on the end of the rod inside the break booster, there is a nipple with a pin (see attached picture) Thinking it also turns out like the screw, I grabbed both the rod and the nipple with two pair of needle nose and wilst trying to turn it immediately bent the pin on the nipple.
The nipple is made out of aluminum and has a little pin that inserts into the rod inside the break booster. The pin is split like a cotter pin and is friction fit inside the rod.
When I bent the pin, I tried to bend it back but aluminum doesn't like to bend and so half of the split pin broke off and the other half is cracked. JB Weld is out of the question as I feel it will eventually break causing a serious break malfunction.
Now the dealer doesn't just sell the nipple even though it is easily bent broken or lost. They want you to buy a whole new booster.
Does anyone sell just the nipple? Or maybe a mechanic on these boards may have one laying around in their tool box? I already checked my local dealer.