Multi-path rejection is something that all DISH receivers with ota suffer from ,regardless if it is built in tuner , ota module or usb ota tuner. This is something that can't be software repaired. The only answer I have seen is to eliminate the multi-path rejection variables to prevent it from happening. Sometimes you have to eliminate the weak ota station from the mix entirely, unless you can aim your antenna to compensate and lock in a better signal. I only tested the tuner for about 2 months before they released it to the public. It was much worse when we first got the tuner. I suffered black screens, automatic reboots, garbled audio, messed up video,etc. I reported each and every bug I suffered and the dish software team worked with me to eliminate the possible problems on my end and they worked on the software to fix it on their end. I would have to say that the tuner is pretty good now. I don't know why you are suffering all the black screens and other people ,including me are not .
I do know that I have suggested many things to narrow down what may be causing the black screens. Something I found out is that if you make ANY changes to your ota application,you know deleting one or re-scanning the channels, ALL of your timers have to be recreated from scratch and your old ones deleted,because they won't work again. I have already suggested keeping your ota tuner flat like the directions say. Rebooting your receiver by unplugging it for 5 minutes and replugging it in is something I have done after new software is downloaded to clear up any problems that may come with the new software. Also something I have found I have to do periodically, and this is not necessarily connected to ota , but if not done , will cause all kinds of problems in the playback of your shows, the actual reception of your sat programming etc,is to run a check switch again. I had problems with live tv not playing correctly, garbled audio,messed up speed up video , black screens on ota and loss of signal on one of my tuners, and a check switch run fixed my problems. I have had to do this twice so far in the two months I was a tester. The DISH software team suggested that I do this and it did correct my issues. Now, I am not saying this will fix your ota , but it wouldn't hurt to re-run your check switch ,just to make sure that variable is eliminated. The only other thing I could suggest is have DISH send a tech out to look at your node , setup etc., to make sure that isn't a problem. After that I am all out of ideas .