One channel is weak. I took it to the Mac authorized service center and they took my money and put in a couple of tubes and said it was fixed. It worked better for a week. I want to send it to Terry DeWick in TN. but all the weight on a 275 (78lbs) is on one side so when you pick it up it falls out of your hands if you don't know about it. Which is what I figure would happen several times there and back. It needs to be refurbished so I'm working on finding someone local to do the work.