While I was inspecting a wood chipper our company wanted to purchase, I found that when looking up from underneath the rear of the machine, there are three rectangular channels welded to the floor from side to side. They are about eight inches wide and five inches deep by the width of the machine, fifty two inches. They appear to be intended to stiffen the floor in the area of the feed wheels. The one closest to the feed wheels, the forward most of three, shows metal fatigue and is broken away from the (good) welds. I know these machines see a lot of vibration and take a lot of punishment doing the job. Has anyone else seen or repaired this problem?