Bill, Melted fuses is normally caused because high current for extended periods of time is going thrugh the fuse. The fuse may and in most cases won't blow . If a cheap fuse is used , then the plastic could be melting prematurally. Littlefuse or Bussman are very common and very high quality and Seimens for our European D's You need to find out which fuse and what is going thru it that i causing the problem.Replacing the fuse may not solve the problem just refresh it. Also, leave off the cover for more air circulation. John 1004