The endless dim problem with the TM751 is well known and has been discussed extensively in the comp.home.automation newsgroup - some people are able to eliminate or reduce the problem by moving the antenna to a horizontal position or my various aother means that I don't recall (I don't use these devices and try to avoid any device made by X-10 as much as possible) -- for more information, you might want to see [Link: rentrondesign.homestead.com]

Good luck, Jim.