These switches also look a lot like washing machine pressure switches, except they have multiple electrical terminals (six or even nine) and don't have external level adjustment. However, some have screwdriver adjustment for both the trip levels and the hysteresis. When extracting the pressure switch from a washing machine, be careful that you don't also inadvertently
If it does not show a reading it means the heating element is faulty. A professional make use of the ohmmeter to read across both terminals once more and the earth terminal on the element. Here however, a positive reading means a faulty heating element while a negative reading mean no fault with the heating element. This is not a job for the average person. If you are not well versed with electronics don't even consider experimenting.