[TowerTalk] EF240X problem

[Mike]

Hello,

Planning to remove the top (145 ft) Force 12  EF240X in the next 
several weeks due to a problem that appeared right before 
Christmas.  The ant. suddenly shifted resonance from 7050 KHz to 7120 
KHz.  Also, the ant. doesn't seem to work as well even at the new 
resonant freq.  Nothing can be seen obviously wrong with the ant. 
looking at it from the ground and at the top of the tower with 
binoculars.  Any ideas on what the problem could be?

         73,
         Mike, K4GMH