I have a 12 ton earth quake cheap model. Bought it for 300.00 used. I need to know if you leave the vent open when running unit or close it. Also on the back, near where you make it go back and forth there is a leak when you send the ram all the way back and it stops on its own. There is a silver cap and it leaks by it. It is held on by two allen screws, no gasket. Is it a easy fix or should I just get use to the drip of oil. Thanks