Looking at a 73H corn picker. All in all looks pretty good. It has been shedded and lubricated. Looks like it could go to the field. Questions - What are things that I need to look at to see if it worn? Wear points? Pros and cons? It has two ID plates - one on the rear of the picker with an SN of 33521AU and on the right side with an SN of 35131AS. He is wanting $650.00. Is this a fair price?