Had the head rebuilt following a premature timing belt break; car has been fine for 12 months. A sharp pronounced ticking suddenly developed in the head - i thought it was a valve problem. Took the head off, had the shop check it, but found no problem. Further research suggested that Hyundai have had problems with the valve lifters blocking, causing them to clatter, and have since brought out a modified adjuster. Question is, how can i determine which adjuster has the problem, and secondly, should i change all the adjusters on the cam where i need to only change one adjuster? i have a new adjuster and it appears to be slightly longer than the original.