So how do I replace this 10Ka 120/240V breaker since my dryer will not heat and I have replaced all its parts. I think I have to replace the breaker (2 pole - single breaker), because when I tested it with my meter, sometimes I would get 120 readings and other times 230 - 240 readings.

Forget the breaker! If you are getting power at all, the breaker is fine. The breaker simply connects or disconnects. The breaker itself does not control voltage control. The erratic voltage readings reported depends on which legs of the receptacle were being read at the time. It is most likely the problem is still in the dryer. Concentrate on that issue & ask again with dryer model details and what has been done thus far. The electricians are here to help.

Where exactly did you test for voltage?

What "all" parts did you replace in your dryer? And WHY?

Exactly,


And WHY?

Parts changing is not troubleshooting the problem.