I just purchased a Channel Master 9521a rotor for my 'older' roof-top antenna. I haven't had a chance to install it yet as the weather here has been quite nasty. I know that there is a really old rotor on there now so I am hoping to just remove that one and replace it with the newer CM one. To those who have installed this rotor already, can you give me any advice or hints/tricks when installing it so that I run into as least problems as possible? I have an antenna tower and the actual antenna is about 3 or 4 foot above the tower (if that helps.) Thanks.