reconditioned engine knocking
 

recently had a reconditioned engine in my 96 wrx, the cams on the right hand side sound like they are trying to get out. :) does the timing belt need changing? or is this a major fault?. the company "Mr Engine" have sent me a replacement after many hours of arguing, but would like to try and solve the problem before paying again to get another engine in. hope someone can advise

tony