Folks, I just had one of my Robart Down and Locked electric motors give up the ghost. I am now considering changing horses midstream and putting in a set of Sierra mains. I know others have mentioned it here but wanted to know if they are a direct replacement for the Robart or does it take a lot of modification to get them in the mounts? I am not afraid of the work, just tired and disappointed and do not want to agonize over this. Any help = greatly appreciated.