I can tell you that I ship hundreds of packages via UPS weekly and whenever I have a claim for loss or damage I get a check from them within 2 weeks.I love the statement ” I have decided to find another engine and put it in top shape”, did you ask your customer if he was alright with that? You also stated ” I understand I am legally responsible”, have you ever herd the phrase morally bankrupt? PLease do the right thing and send the man a check !
Looks like you a getting the run around here. If it were me and I paid with a credit card I would dispute the charges,remeber you only have 60 days from receipt of statement to do that. I would also give Mr Barth a time limit to settle on the balance and if that day comes and goes I would file in small claims court as he wishes.