Need a little help. I have a Roland Versacamm 300 VS. I'm changing the pump however, the newer pump models have 4 ports but there are only 2 lines coming from my captop and 1 line going to the waste bottle, 3 total lines. The new pump has 4 ports. I've been told I need to "cap off" the extra port on the waste side but how do I do that? The new pump did not come with any kind of extra cap.