Here is a video of How to Split a NEFF, or Bosch Oven Door with the trangles on – the triangles refer to the trangle shapes in the corner of the inside of the doors. The oven that we had in our house was one of these and I used to train all our new employees on it. It wasn’t until a couple of years after we had moved out of the house that I discovered that you could actually take these doors apart. I went to a house where the lady insisted that I took the door apart and presented me with the manual. I found the right bit and took it apart.
I have always found that when you take the outer door off the inside is usually perfect and you really have to be careful not to make it dirty. So I only take it apart when it really is necessary and this is usually when you can see a run of dirt inside and then it is a case of opening up the door and quickly taking cleaning the door and then putting it back together.