When I had a DeLaval 73 I put a ipe on the exhaust that was 6' tall. That helped keep the oil in the pump and only the vapors came out of the top. I then had that exit into a 5 gallon bucket near the top. The vapors would condense there so that near by object didn't get covered with oil.

Your pump could be turning hard because of a sticking vein or lack of lubrication.