too many problems to list controller and doors is the usual Otis bullet proof stuff but the machine and motor are junk, basically throw away. If they have those nasty flat rubber cables that's even worse unless you had a master mechanic install. you can tell by the wear of the treads if your gonna have issues. I won't touch these things, Otis loses their ass on these so I can't imagine anyone else doing much better. I'm in the process of scanning my Big O manuals to PDF when I'm done I'll let everyone know. I won't post them but I will email them to you. I'm also scanning all my TK, Kone,and Schindler stuff. That will take at least another month as the printer I use takes awhile and is kinda pricey to do this.