scientific atlanta 4240 HDC aspect ratio problems

The Scientific Atlanta 4240HDC will not change the picture size of either of my SD tvs when I change the aspect ratio options in settings.  and the HD zoom button does not result in a change in the picture size.  There are lines across top and bottom of the picture.  I thought it was my Magnavox SD tv, but then I got ahold of a SD Sony and the same results.   The Cox minibox will expand the picture, but I need the composite and s-video connectors, for use with my vcr,  which the minibox does not have.   please  a solution????  I enquired back in November and never received a response.  

the tv picture will not change even if the vcr is not hooked up.  

any live chat or call to Cox has not resulted in any solution. 

thanks,