ZNew = GetVar(2002)
This is the Z position at your touch plate, and will change every time you probe. It's in work coordinates, and the value can vary greatly, depending on the current Z offset.
Code "F2" 'slow down feedrate to 2 ipm
ZNew = GetDro(2) - .25 'probe move to current z - .25 inches (current setting .77...)
Code "G31Z" &ZNew
This is a second, slower probe move. DRO(2) is the current Z position, so it's probing down .25".
When you are stepping through the code, if your not actually probing, you may get strange results.
Also, make sure your in Absolute Mode (G90) when you run this macro, or you'll also get strange results.