Thermador display is very dim

I am having the same issue-dim display. I can see the clock but not the temp. I have a Thermador wall oven with microwave on top. (It was in the house when I moved in.) How do I find out what model number I have and which part to buy? How easy is it to replace the part? I’m handy but I don’t want to make it worse if I can’t fix it myself. Thanks!