Workhorse got a lot of publicity for a brake recall. I have a WH that needed the recall but I also had a Ford chassis that had the same problem. My mechanic at that time explained how brake fluid will absorb moisture. When you have the moisture in the lines is permits rust to happen to the interior brake parts. My Ford experience was on a 2 year old chassis in '91. Since then I have flushed brake fluid every 2 years. It is a simple job and my son & I can do it in 15 minutes. He is the one who gets under the MH!!