I am puzzled to a point I need to ask for help. I have a Lesco Skid 200 gal sprayer with a D403 Hypro pump. The other day while using it all of a sudden the pump oil resevoir looked like a black and tan. I replaced all the diaphragms in the spring. So usually when the diaphragms crack it turns the oil milky and it drains into the water, pressure goes bad, and oil is gone. Today I took off all 3 heads, inspected the diaphragms and no issues. Put is back together and ran it. After 20 minutes oil back to a milkshake. What else do I need to look at? Should I replace all 3 diaphragms even though they look good? Ideas, thoughts?? Thanks in advance.