Neff Double oven 1410/1420

Question

Hi

The main oven fan is intermittent. It will come on full speed sometimes. I can nudge the blade round and it will pick up speed then stop. It doesn't seem to be the actual fan/motor itself as it will run full speed sometimes.

Thanks for any help, please don't suggest I get soemone in to fix it as I am perfectly capable in replacing motors, checking for voltages etc.

David