Maybe I'm naive here. But I really don't get the "boneyard" concept in airsoft...why is so much airsoft gear (mainly guns and mags) sold when it could be only described as "fucked"??? I wouldn't even dream of selling (or buying) anything that wasn't in 100% working condition.
Imagine going to buy a used car. Theres a three year old Mondeo for sale at full RRP (bizarrely). It only runs on three cylinders, half the front bumper is missing, the aircon is shagged, two of the tyres are bare and the brakes are juddering, but don't worry, the owner reassures you "its a simple fix mate".
Nope, neither would I. Whether it was a hoover, a Honda Civic or an airsoft gun, if its pumped, its not fit for retail. Sorry. Fix it, then sell it.