Changing to 65% should have no affect on your tune unless you were on the edge of the arrows spine. The 65% module will boost your power slightly and may have put you off the arrow's capability (out of the arrow's spine limits).

The other possibility is the installation of the module was not done correctly. This would be just about as rare as what I stated above; but, it's possible. Sorry you're not closer so that I could help you personally.

Did you check to make sure you replaced the 'E' module with a 'S' module and that you put the screws back into the same draw length holes?