Identifying pcb component
It is black, circular about 6mm diameter and 2mm thick in this case.

If it looks like one of these: -

...then it's probably a disc thermistor of some type but, it could also be an MOV transient voltage clamper or maybe an inrush current limiter like this: -

It's still a disc thermistor as per the top picture but more modern devices fully encapsulate the soldered lead to prevent corrosion.