Update: Replacement parts

Yesterday I received by post two replacement parts from the manufacturer: a new connection arm and a new cylinder. My first question was: How can I be sure that the replacement is not as hollow as the broken one I have in my hands?

A quick visit to the nearest Post Office was enough. The broken and hollow one weighs 7g less than the replacement. That is a more than 10% difference between two parts supposed to have the same dimensions, made of the same material and part of the same high end product.

A simple checkweigher would have detected such gross discrepancy,  rejected the defective part (for an inspection, perhaps?)  and prevented the accident. At this point I would prefer to believe that the manufacturer has an ineffective quality control / assurance in place (if it does), rather than it is deliberately placing defective products on the market.  How many other "time bombs" are out there??