I got pictures of how the pipe is held in. The simplest way I can describe it is that it is sandwiched between the lower unit and the powerhead. It does look clean in the pictures because I cleaned it and haven’t ran it since. 
I haven’t really tried to make a gasket yet, because I wanted to know what any possible solutions were. There really is nothing to torque down, and the machine screw at the very end of the pipe where it meets the lower unit is to keep the pipe from rotating with vibration. Hopefully the pictures help, and if I need, I can always take more.
