I am looking at a 25 year old Evinrude to purchase - problem is a mechanic tested the cylinders and reports that three are producing approximately 130, 125, and 110 lbs, BUT one is at about 5 lbs. Thus, no compression in the fourth cylinder. The engine otherwise seems to run fine and checked out. The mechanic told me that the faulty cylinder could cause the engine to fail at any time (,or could just keep running for a while). Any advice would be greatly appreciated. Thank you.