My 5 year old 7200 has been overheating and shutting-off after about 20 minutes of running at ~ 6mph. I replaced the expensive lower control board without any improvement. The motor never gets very warm. I'm not sure if the tread belt is worn...I removed it and the inside is a dark brown. Not sure what it looked like new? The black surface board appears in very good shape. I've applied silicone spray (Gunk) from the sides as I've used it. I've put a lot of miles on it as I used it to train for a couple of marathons...and could regularly run 2-3 hours at a time with no problems. The phone tech suggested it was because the machine is in the basement? I'm just wondering if the belt is the real problem (does the new belt have a silicone/slippery surface? I've even switched from a 15 amp to a 20 amp power source..both have 120 volts to the plug. I recalibrated treadmill but this didn't help either. I can run the machine at 11mph for a half an hour with no heating of control board if no one is one it. Thanks for any ideas! Rick