ProForm 760 treadmill problem

PegasusDeb

Please help!
I have a ProForm 760 EKG treadmill that is about 10 yrs old. I have had it since it was new. I haven't had to do any maintenance on it. I have up'ed my walks to 2 miles & since then my t'mill gets over heated. I thought it was the surge protector, because the cord was getting warm. Well, I changed that out & tonight the plug & cord did not get warm. But it is still over-heating cuz you can smell the heat. I have adjusted the belt, and thought that was it, but apparently not. It seems to smell hot on the left side. I've been reading different webs & alot say that the belt needs lubing, the manual says there is no need, but I wonder if that would still be true, since it's 10 yrs old! I did raise the incline to see if it would slide me down to the bottom. It did not. Which they say means it's dry. So that will be my next step I guess.
Any suggestions please feel free to comment! Thanx!
~Debbie~