Is it the case that Metropolitan line delays have been caused by the wrong calibration on the lathes by the manufacturer, making the wheels too small to run?

Routine checks to the Metropolitan line fleet identified an issue with some wheelsets on the trains. The wheels identified were not too small to run on the tracks, but presented issues which meant the affected trains had to be removed from service whilst remedial works were carried out. The root cause of the issues identified will be subject to a formal investigation.