Just noticed your post (2 weeks old) but it caught my interest. Our 15 year old treadmill started acting flakey a couple of months ago - and finally stopped running last week. Some error code popped up and when asking for a diagnostic of that code, the tech sent me to a treadmill "help" site. I found that site interesting, in that many of today's Brand name units are not all that reliable long-term. I also realized that my unit was old enough to cause replacement parts expensive and hard to locate.
I went through the little survey which attempts to match machine with user needs and came up with an idea of what sort of new unit might cost for my wife and me ... and an idea of a new treadmill's limitations.
A unit like yours which is approx 9 years old might be nearing its age limit. Of course, it all depends upon the components. Most of the working life of the new treadmills I read about are pretty much in line with the basic warranty which accompanies the unit.
Good luck with your repairs.