I had a similar problem with my 3765. After trying to align
the touch screen dozens of times with the back light on,
I stumbled across the fact that if I aligned the screen with
the back light off and use it with the back light off it works
fine. But anytime I turn the back light on the touch screen
alignment seems to shift and becomes rather useless but
otherwise the programs seem to run fine. Since glider flying
is typically done during daylight hours having the backlight
off is no big deal.

M Eiler