Always calculate the cost of engaging the manufacturer. Call them and ask them how much they charge for an engineer to help you. If you see yourself approaching

Always calculate the cost of engaging the manufacturer. Call them and ask them how much they charge for an engineer to help you. If you see yourself approaching what looks like it would have been cheaper to explain to someone and have them give you the result, take the plunge. Sometimes it is a manufacturing or design defect. Pay to learn, and ask the manufacturer for a refund if you really do find a defect. Don't ever tell the client you're unable to complete. Take a small loss, learn a small lesson, and deliver like a champ. They will think you did all the work, and with your new knowledge you will be able to deliver the same work for many clients in the future.