I've seen devices with flat plastic cables where the conductors were "painted" on.
Membrane keyboards sometime have these.
They are cheap to produce but not very resilient, as you have found out.
When the cable flexes, cracks appear cutting the conductor.
If the cable pulls from it's compression socket, it often cracks when one re-inserts it.
That could be the reason they seem difficult to find.
If your cable is shot you may be out of luck.
Perhaps you could make your own compression connector.
Measure the conductor spacing, if it is 0.1 inch you are in luck.
This is a standard spacing for 'perf' boards like Radio Shack's 276-1688.
You could cut off 16 traces worth and build up the surface with solder.
Fashion a clamp of some type and however you want to hardwire it.
Seems like a lot of work, but so is running the treadmill.