Joeys freezing up/no signal

A few weeks ago our Joeys in house (3 Joeys, 1 Super Joey) began freezing up and then displaying no link to Hopper, then after a few min the picture will return only to do the same thing again. First we swapped out our original Hopper with Slingbox and it didn't help. Next a Dish guy came to the house and discovered a problem in a node and redid the nodes and the LNB on the Dish. Still the problem continued so Dish came again yesterday and spent 3 hours on it and ran a new line from the Hopper to outside components and also reconfigured the way the nodes were setup. They also replaced the Hopper with Sling again just in case. It seemed like it was fixed but last night the Super Joey froze up and today the Living Room Joey did the same. I don't know what the problem is. We had this service for a year and a half without any problems and now it doesn't seem to be working right. The Dish guys that came were very helpful and knowledgable and I'm not placing blame on them. I just do not understand why it won't work correctly. Does anyone have any ideas or had similar issues? We are ready to switch to Directv just so we will have a working system.