Multiport problem

I have a similar problem with mine and I can get it to quit if I do the following. My filter looks very similar to yours.

I use the handle at the top to rotate it through the various settings on the pump, sometimes working it into each one of them. I will then usually move it back and forth, clockwise/counter clockwise, and then choose the filtration mode. When I do this, it usually quits leaking out the port. If this doesn't work the first time, try it again, mine sometimes takes a couple of times to make it quit.

I've also thought of using the winterizing plug that I put into the pool wall fitting (it has a rubber stopper and a butterfly nut to tighten it into place). Since there is no pressure, I think this should work but I haven't tried it yet (since the above procedure seems to work for me).