First of all never mention anything in the ad that isn't for sale.

What I mean is you just have to assume people are stupid (and they are...trust me) so you should only say, "I am replacing it only because I bought a newer tv" thats it no more and no less. They don't need to know you got a plasma because as you can see people use selective comprehension when looking for something they want.

Edit your ad and problem is solved