Just something to clarify on the troubleshooting.
When you "swap" cables... test each tuner "alone" one cable at a time.
I've also been noticing/using DTV's "Test Channels" 490 and 491 which give you a visual confirmation of getting even (18v) or odd (13v) transponders on Sat 101.
As rocket said it is likely that your UTV may have a fried tuner (you may have to disconnect the "bad" one and go with a single tuner until it is fixed/replaced)... But it may be worth it to confirm that your UTV isn't suffering from overheating or that there are any weak links in the Dish Setup which, if fixed, may keep Tuner 2 happy.
Make sure you check your UTV's LNB settings are correct. You might also use the "advanced" Signal Strength option (accessible via "Dish Pointing" in settings) this allows you to verify the Multi-Switch (if you have one or not, it checks the feeds for proper voltage/signal) can supply both even and odd transponders. I've been able to bring back some Tuners from the "dead" by using this option. (Where cold boots and cool downs didn't seem to help)
In my opinion you may also try and bypass the Multi-Switch to verify a "direct line" doesn't fix the issue. With that said you may also try swapping the lines at the Dish to confirm you don't have a bad connection/cable or bad LNB in your setup, that Tuner 2 doesn't like.