I don't think it's possible for a lamp module to boost signal, in-fact generally the more x-10 items added the more problems that occur. Perhaps somethings changed since the problems, has something been unplugged or relocate? even some other seemingly unrelated device being turned on or off can make the difference.

When I first started my system with just a few device's all worked great, after adding more I started having the same kinds of problems that you are experiencing. I filtered all tv's, computers, and the like, I also added in a CR234 coupler/repeater. Since this I am up to over 30 x-10 devices and have perfect results.