Decades ago when we had more OTR driver traffic a driver would get sweet-talked by some truck-stop tweaknician who would claim "I can get more Watts from that radio" without asking how many it delivered already. And when it broke another hundred miles down the road, he'd bring it back and claim "It just quit".
Yeah. We started using the tamper sticker until the nearby tweakers figured out where we bought them. Tried some custom stickers but they were too fragile and would crack between the top and bottom cover even if they were not disturbed. Not useful.
We settled on a simpler tamper indication.
Missing case screws. Seriously. I figured the truck-stop clowns had a "screw tax" and built a collection of screws by keeping one from every radio. Maybe. Only had to ask a few times how that screw went missing if the cover had not been taken loose since we worked on it. Made it clear at a glance somebody else had been in there.
Eventually this trade dropped off and the problem fixed itself for the most part.
I do remember one base-station operator from about 50 miles south of here. Just couldn't resist tweaking, but he was honest about it. He'd show up with a radio and announce "I put another one to sleep". He was a good-natured old fella.
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