Another slide-out won't retract but slightly different scenario?

[mooseherd]

First: 2013 Windjammer 3008W

A couple years back, we decided to become seasonal campers. Never had a problem with the slide-outs until last fall. We were putting her to bed for the winter (Sarona - somewhat northern Wisconsin) and the bedroom slide came in as normal. However, the larger main room slide started coming in and I noticed it was going to hit a handle above the TV (if you know the layouts, you'll get it and if not, just know that it's not supposed to do that!) We ran it back out and tried again. Same issue. We ended up leaving it out for the winter. When we first got up here this spring, I got under because to me it seemed like it might have slipped a tooth (I have no idea how, but it seemed to make sense.) I carefully measured both sides and they are the same so that is not the issue. Everything under there looks "healthy". Kind of at a loss.

We have six sets of cement blocks and wood under the frame of the trailer. Two in front, two in back and two in the center. I noticed that I had put the center one under the slide and about 2/3 to one end. My thought is that perhaps that pressure might bind the slide (specially if the ground shifts at all)? I will be re-leveling this summer, anyway, and wonder if I should try to move that stack either to the center of the slide or away from it completely. Or is that unlikely to be the issue? It won't hurt to try, but I'm wondering if anyone has any thoughts on the subject. Thank you!