Point is, any tank that is 50 or 60 years old is going to have quality issue. Regardless of origin.
As for quality of Chinese equipment, it depends on the timeline: tanks, jets, ships wether it was manufactured in 1970s 1980s or in 2010s & 2020s. The state of chinese MIC is vastly different than what it was 40, 30 or even 20 years ago.