Slide-out floor getting soft

[Bill]

I have a question for slide-out owners. In my unit, the floor in front of the couch has gotten quite soft and flexible. I peeked behind the rubber lip and found that the floor is supported by two little wheels (casters) under the edge of the floor, just behind the lip. These are spaced 1/3 of the way and 2/3 of the way across the edge. However, there is no support under the middle of the floor, and since this is where one normally walks (at least when the tables are up), the floor flexes. The flex has gotten worse, and I am concerned that the floor material (presumably plywood) will come apart.

I have taken to shoving a piece of 1x6 board under the rubber lip, to support the floor, but this is ridiculous. Has anyone else has this problem? Any suggestions?

Bill