Thanks for the tips. I give my full guarantee that this marker works perfectly and that the buyer will be happy with the performance. I really don't have the time to search for screws, and I think that if someone is going to offer me a lowball because of something like that then they aren't going to pay a higher price even if those minor things are corrected. I could fix it up, replace the screws, get a new feedtube, stuff hundred dollar bills in the barrel, but you are right: it won't sell.
I will continue to bump this thread every once in a while, but I will plan on holding onto it. If nobody wants to buy it at the price I'm asking then that's fine; I'm not giving it away.