truss rod adjustment

Hi guys, I got my strat today and noticed its neck is a bit concave. I tried to adjust its truss rod but I couldn't because it was getting very hard to straighten it (turning clockwise). I had my strat adjusted during the winter but now I'm afraid the truss rod or the neck is screwed. Have you...

The idea for this thread came from a concurrent thread. Recognition and Thank You to jbealsmusic for some of the wording and for (unknowingly) prompting me to start this thread . For this discussion, it will be understood that the guitar being adjusted is NOT poorly made or old and fragile...