Just a final followup. As Scott noted, It turns out that the battery compartment cover was loose and snugging it up well stopped the malfunctions with the second optic. We ended up shooting it for another 6 months at about 30 rounds per weekend with no issues. Just had to snug down the the cover occasionally. Since we closed the rental business last year, I just removed the optic today and it now lives on the wife's suppressed 15/22 rifle for a quiet and peaceful retirement. A new Aimpoint Pro is now on the Beo. Let's see if it can match the Sparc in recoil tolerance.