Nano looped to Bell pvr

I have had my nano receiver and my bell receiver looped together for a couple of months now. All of a sudden I can only get a signal on certain channels. The nano will work fine as long as it's hooked up by itself. Once I loop in the bell receiver I lose signal on the nano, but maintain perfect signal on the bell. Any ideas?

Yah, it should have never been hooked up that way, the bell receiver has fubar'ed your nano's output for the loop through, this may have also fubar'ed the main tuner.

It would have been better to run a second coax for the nano, now it's to late, no way to fix it now.