Sentence:Notwithstanding the use of special assembly techniques, it is currently quite common to find, downstream of the assembly line, known radiator caps with the small [e1]spring[/e1] of the low-pressure [e2]valve[/e2] imperfectly aligned with one of its necessary bearing surfaces and/or with the shutter, which leads to unpredictable operation of the radiator cap and consequent rejection of the product.
 e1: spring. 
 e2 : valve.
Answer: Component-Whole(e1,e2)