When trying to pump out, the waste water surges for a few minutes, which indicates that air is not getting into the system, someone with a little experience with the system told me. Apparently, the vent is on the side of the hull a little forward of deck fitting. This person said to funnel some Jet Dry into the vent and let it dissolve the blockage, but I have rigged a clear plastic siphon, and the cleaner is standing in the siphon tube, so it looks like this isn't working. I would like to know if this is actually the vent port and how I should proceed to clear the vent tube.