If you're handy with a soldering iron and have at least a hobbyist background on electronics, you could try to "fix" your preamp, if that's indeed what's wrong with it. If you do a search on TV Fool, you should be able to find some good, clear photos of inside your preamp. I think rabbit73 posted some a while back. If I can find them, I'll post it here.
Otherwise, I would recommend you read through this thread before you buy another RCA preamp, due to quality control issues this model has had. You were lucky to get a good, trouble free one for the five year life it gave you.
http://forum.tvfool.com/showthread.php?t=16768
Anyway, KevinTMC, just my two cents worth. I'm sure you'll come up with a solution that will work for you.