I had a flaky lnb that kept causing tuner issues, can't prove it but I think it stressed T2 on 1 HR20-100 to point of failure. it was extremely intermittent, sice I had some older cabling anyway I replaced it all to rule it out. I did find a bad spot, but it was on an unused drop. at first I thought issue was fixed but a week later back to normal, both dvr's dropping tuners. I replaced lnb and 1 unit was fine (until fan started smoking ) from that point on, the one used most often never fully recovered.