Hotpoint Wf541 Door Interlock Broken Twice

Hi, I have a hotpoint WF541 washing machine, and halfway through a cycle the 'door locked' light started flashing, the cycle stopped, and the only way to get the door open was to turn it off at the mains for a few minutes. If I tried to start a new cycle the 'wash'light came on and the door locked, however the door lock light didn't come on and the cycle wouldn't start.

I figured the door interlock was broken, so bought a new one. I fitted it, and everything now worked perfectly. However after putting a new cycle on, it got halfway through the cycle and the same thing has happened again to the new door interlock. I.e. I press start cycle, the door locks but the door lock light doesn't come on. The cycle doesn't start and the only way to release the door is to turn the mains off for a few minutes.

So, was I just unlucky and got a duff replacement interlock? Can the machine have a fault where it damages interlocks? Could the problem be something else, and it was just chance that it seemed to work after fitting the new interlock? Any help appreciated!