If your talking about the skylight lift 
mechanism then yes there is... Found right on the first page of a google search..

http://www.vanagonauts.com/[75.6a]-Roof-Vent-(Skylight)170.htm

Good luck

Bill
87 Westy 
Zetec Turbo 

Sent from my iPhone

On Jul 7, 2013, at 2:55 PM, Jim Ogul <jimogul70@GMAIL.COM> wrote:

> My Poptop lift mechanism keeps coming of the tracks because the little
> wheels that keep it on track are broken.  Is there a hardware store fix for
> this?  Anyone have a do-it-yourself fix for this.  I kinow you can buy a
> replacement for the whole mechanism but I'd rather fix what I have.
> 
> Jim
> 85 Westy