If you are seeing little gaps between the side strips and the center strip it is because the side strips are slipping in their retaining grooves. You do not see a problem like this on the older (pre - 123 ) models because the side strips use little clips to hold them to the screen.
Problem & Solution
Common among these chassis:
The side strips on these models have grooves on the back side that slide over notches in the plastic screen. This allows them to move side to side. To keep them from opening up gaps like you see here, use a small dab of silicone or E6000 glue on each strip to hold it in place. Just open the hood and apply the "small dab" to the back side where it can not be seen. Push the side strips toward the center until they touch the vertical strip and let dry overnight.