Tomorrow is the day to repair it. Today i just ran down to the boat to check on stuff and had a few moments to clear the vent of the vented loop. Two years ago I replaced the nipple with a Yadina 4-5 inch plastic tube and one-way check valve. The theory being that waste would rise the extra four inches and never reach the valve which would never get jammed with debris. Well the waste went up the clear pipe and jammed the valve and then retreated. Its clear that I have/had a blockage. I cleared the valve and tomorrow I will do the exploratory service. I highly recommend this product from Yadina.