I had to replace mine because it the unit kept getting turned on in the rifle case. I really think they installed a switch with backward settings. It turns on easy, but you have to press and hold several seconds to turn off. The logic, as I understand it, is that you don't want it accidently being turned off in a crisis. The Sparc isn't exactly a battle optic, however.
"If you look through your scope and see your shoe, aim higher."
-- said to me by my 11 year old daughter before going out for hogs 8/13/2011