My brother-in-law had the opportunity to buy an older Hobart unit and we have been trying to find out more information about it. The serial number on the plate says "7J-2171". It looks like a previous owner removed the operating instructions off the inside cover of the control panel, so we don't even know how to fire it up to see if it is still operational. If any of you have an idea of the model, year manufactured, and/or could steer us towards where to find a user manual for the unit, it would be much appreciated. Thanks for your help.