Been running Yong Heng for 8 months. It stopped building pressure and lots of air now comes out of the breather valve. I've torn down the unit and found that the tip of the 2nd high pressure (gold) piston was broken. I replaced the piston. Also changed a broken o-ring in the high pressure check valve. Fired up the compressor today and still have a problem with lots of air coming out of the oil fill breather valve. Any suggested solutions?