About every 3-4 years on ly 77 450 sl, awindow will"freeze up". Before you take anything apart, try spaying with extnesin nozzle, wd-40 into door around morot and scissors mechanisism. Check glass for alignment. hold door open, pull up or push down same time as trying switch. I did this 2days ago window works fine! No ned to dassemble anything Try this first! Abe G