As mentioned in the other thread there very well may be ice-glycol buildups within the hinge gaps near elevators that can inhibit movement. Only a deliberate check for them by moving the elevator will find them. I have never seen them myself, but they are supposed to be big enough to stop the flight surfaces from moving. The airplane would have had to have flown recently and been deiced recently for this to happen. It happens when the residue from previous de-icings gathers in crevices and refreezes by admixing with moisture from clouds. I am not sure how this could play into the uncommanded pitching up problem.