Hey, Skladfin, I have a similar sale issue too recently.
I have traded my EOtech 551 with a well-known ASC member for his CA mags. The EOtech 551 was working before I sent it to the buyer and then the buyer PMed me about EOtech 551 not working after he received it.
So, to my best customer service (and remember I'm not a retailer), I offered to take EOtech 551 back and sent him my EOtech 552. I double-checked to make sure EOtech 552 was working before I sent it to him as well.
When I received my EOtech 551 back, all I observed were oily fingerprints everywhere including the screens, and the reddot has become a red blob with no reticle.
Should I trust this buyer's story that EOtech 551 wasn't working?
Note that both EOtech 551 and EOtech 552 were brand new, never used and fielded, only checked to make sure they were working.
There are many well-known ASC members but yet their morals may not be as well known.
Just my story to cheer you up, because I lost $85.00 USD for this simple transaction, and you haven't lost any yet.
Velocity, Distance, Acceleration, Time...
A gun has them all...