I have a microwave oven which timer button is broken. I would like to fix it (by using glue?) or replace it (with a similar "key"). The oven is a Samsung M1714.
However, I am afraid of making things worse if I try to repair it, and I do not know any shop where I could buy something similar. I noticed there is the number 3 written on the inside of the broken piece.

Do you know an online shop for this kind of thing?
Here are several shots:


