1) someone out to sabo the people involved, the item probably ended up in some ulu part of the camp, all smashed up.
2) the guards sleeping, therefore deserved to be charged
There was the usual conspiracy theories. The most "plausible" one, albeit speculative, among the men was that one of the regulars (the BC or DO or BOS or whoever) removed the equipment to teach a lesson - kinda like a BMT instructor stealing an unattended rifle - then panicked at the high-profile fallout of the loss. Theoretically, none of the peng was rich enough to drive cars into camp like the regulars, & it was also politically incorrect to search their bunks or, at the camp gates, their car boots.
We did hunt around our areas a lot, though, as well as those of our sister SAR unit. The GDS unit at the other side of camp (different gate) orbited around its own planet, so we didn't venture there.
I personally don't think the sentry guards slept. The discipline was potentially more lax during field exercises but, if you've ever done standby, I think you would've appreciated how highly-strung the affected troops could be. It's likely doing normal camp-gate sentry, multipled by a week. Your ear was always listening for turnout/activation, you slept in your No. 4's &, when it comes to nightly guarding of vehicles, you'd more or less rotate sentries by hour or every 2 hours. There's no real letoff of tension; everyone's very on the ball.