Will a tuner cause low signal strength?

I have 2 Premiers and 1 series 3 all running off an OTA antenna. No cable or satellite. Signal strength on 1 premier and the series 3 are perfect, in the 90's. On the other a Premier in my living room, signal strength on some channels is bouncing in the 40s and 50s which is almost unwatchable. They are all running off the same splitter. I have switched cable positions on the splitter and have also run a new cable just to make sure it wasn't a connection problem. Is it possible the tuner in the Premier might be going bad or is the cause of this issue? I have no idea what else to try, so I may just end up swapping units with the one that works. I really want all units to be functioning at 100% though. Any thoughts would be appreciated.