I worked in retail for many years & was told that the plastic housing turns yellow because of the artificial lighting that is used. This happens in the home also. Unfortunately I don't think there is much that can be done about it, so if you see a whitegood product on sale & it's yellow it usually means this has been a floor model. Ask for a discount or new item.
Irene

artificial lighting is flourescent lighting or similar
Irene

Well, I haven't had this problem with my machines, but the handles and trim around the ice dispenser of my refrigerator did this! And, I have huge flourescent lights in my kitchen. Wow, never knew this. Thanks for the reason, but I still hate my 'yellow' handles on my white refrigerator. Hugs, Marji

I suppose the material turns yellow by age, just as we turn into grey.difference is we can do a bit cheating with paint and make-up LOL

I DON'T KNOW IF THIS WORKS, BUT SOMEONE ONCE TOLD ME THAT IF YOU EXPOSE YOUR YELLOWED PLASTIC ITEM SUCH AS A SEWING MACHINE CARRYING CASE TO THE SUN - ACTUALLY LEAVE IT SIT OUT IN THE SUN - NOT SURE FOR HOW LONG EITHER - THAT IT WILL LIGHTEN. THIS IS PROBABLY NOT A GOOD THING TO DO WITH A SEWING OR EMBROIDERY MACHINE THOUGH. IF ANYONE TRIES THIS - LET ME KNOW IF IT WORKS. MY WHITE REFRIGERATOR HANDLES ARE A LITTLE BIT YELLOWED. IF I COULD GET THEM OFF WITHOUT DAMAGING THEM I WOULD TRY IT.

Excessive heat will turn plastic and coated metal yellow sometimes.

yellowing is due to photons contained in sunlight :o)
To remedy this, we can use hydrogen peroxide or.... Vanish cleaner (don't know if it is found everywhere in the world) or...or place the object under a sun lamp WITH UV*