This 19 February 2020 video says about itself:
Boeing is facing more problems with its 737 Max series, which have been grounded for almost a year over safety concerns. Recent inspections have found debris in the fuel tanks of several planes awaiting delivery to airlines. Also today, we look at the latest from talks between French unions and the government over the controversial pension reforms.
Translated from Dutch NOS radio about this today:
It is not entirely clear what the waste material is. Boeing makes no statements about this; according to some media, it is tools that had been left behind during manufacture.
It is also unclear in how many planes the waste was discovered. …
The 737 MAX has long been a worry for Boeing. The fatal crashes were found to be caused by software errors in the operating system. …
Internal documents from the US American corporation showed that staff had long doubted the safety of the 737 MAX. “I would not send my family in a plane the crew of which was trained with a MAX simulator,” an employee was quoted.
Another former Boeing employee told US media and a committee of inquiry in December that staff at the 737 MAX plant were working overtime structurally, while everything was lacking in the workplace. This would have led to errors and unsafe situations.