I cleared everything from the "junction" that was in my system. You can see it in this old pic from below between the pump basket and the skimmer/main lines. I removed the plug and went to Home Depot to buy one that would screw into this that would also take the vacuum hose attachment screwed into it.
This is an easier way. You have shut off valves for all 3 lines. This makes clearing the return side easier as air can only to that way. I am glad you were successful in the closing of the pool. I just added the winterization of the sand filter to the first post.