Rick,

If you are using the split-Y elevator control rod, it may be that one of the Y is flexing more than the other under load. If this is the case than you may want to use the MK bellcrank to drive two elevator halves more accurately.

Also, you want to do the lateral balance with the wing on as the engine muffler position or equipment location in the fuse may cause one side to be heavier than the other.

Azhar