These can fail randomly but signs of failure are ticking tappet style noises at idle, either when cold or hot. These noises will go away when you blip the throttle or rev the engine. If left, it will stretch the timing chain and push your timing out, causing loss of power and poor running. The fix is to replace the TCT or Timing Chain Tensioner with an upgraded one from either TODA, Ballade Sports or OEM. Its takes about 30 mins if you work slowly and methodically. This can easily be undertaken by a competent home mechanic following the many guides out there on YouTube.
It is quite common for the OEM replacement TCT to suffer the same problems so nearly all owners opt for one of the upgraded parts.
I personally do not recommend the sand blasting or refurbishing of your original TCT. Microscopic debris can embed into the metal surface and is only released when in contact with hot motor oil. This is not good for any engine.