After looking into this problem further, I noticed the bed was looser when it was towards the front than towards the back. I checked the distance between the aluminum extrusions using a 12" digital caliper & noticed at the back it was 209.38mm & front was 208.87 fron Outside to Outside of Aluminum extrusions. I loosened the screws on the new plastic endplate & pulled the aluminum ends to the outside while tightening the screws & that tightened it up just right. This bed was also loose with the wood endplate, so am not sure that the problem was not there before changing this. I will see how this correction works for awhile, before possibly redoing that endplate design to make it easier to fit.