For those who've been having problems with the ChannelMaster CM-7000PAL tuner intermittently crapping out and not receiving any stations, this may help.
I'd posted earlier a theory that when the CM-7000PAL's tuner stops working and registers a zero signal strength on all channels, there might be a correlation between that and the CM-7000 picking up out of market signals for just a quick minute, adding them to the channel list, and then the tuner giving out.
For the last month or so I've been deleting these out of market channels after the CM-7000 adds them. And my tuner hasn't given out once, not one time. I really believe the unit's tuner tries to pull these signals in repeatedly after adding them, and then maybe heats up(?) and then stops functioning and trying to receive any channels.
To anyone who's having problems with their CM-7000PAL tuner, I would advise deleting out-of-market channels or, as an earlier poster pointed out, blocking these channels, and then seeing if their tuner behaves more reliably over time afterward. My tuner has never worked better since I started doing this, no lockups or any other problems at all. It's anecdotal, and I have no technical information to back it up, but it's working for me fyi.