Pump and sprayer worked fine last week... but today was 25 degrees and I think the pump may have got some ice inside. The oil going to the diaphrams (where you fill the clear, plastic cup/gage) started disappearing. It wasn't milky like when the diaphrams crack and mix with water..... it just keeps getting sucked into the pump. I've refilled it 3 or 4 times while running and it just keeps going out.... it's not leaking on the outside. Diaphrams were replaced about 1.5 years ago with little use since. Any ideas?????