Did you end up swapping the colors after finding it or just leave the old file alone?

Damn that sucks man. I had almost the exact same thing happen with a used power meter I grabbed off Craigslist last year. Paid $500 for it and spent three weekends pulling my hair out over fiber readings that made zero sense. Turned out the internal reference was shot and the unit was reading everything 2dB low. Got so frustrated I finally borrowed a buddies Fluke and found the problem in ten minutes. These cheap online deals are a total gamble, especially with fiber gear that needs calibrated lasers and clean connectors. Never again for me, I'd rather rent a known good unit for a week than waste months on some junk from eBay. You got burned hard but at least now you know the real cost of saving a few bucks.

Oh man, that cat story is brutal but also kinda hilarious. I've been there with tech that sounded great on paper but turned into a disaster. What really helped me out was just getting a simple telescoping mirror and a high powered flashlight. You don't get a video feed or anything fancy, but you can see cracks and buildup pretty clear if you angle it right. Plus no animals try to fight your gear that way. Might be worth trying before shelling out for a different expensive gadget.