Need help with discoloration on my Kenmore
 

I have a model 158.1941 Sears Kenmore sewing machine that is now 39 years old. It is a workhorse and has only needed repair once which was my fault for being in a hurry to finish a corduroy/shearling lining coat for my DH and cracked the bobbin case. Anyway, the side panel where the hand wheel is has turned yellow. That is the only part that has done this, all the rest is the cream color it was when I bought it.
Is there anyway to turn this back to it's original color? Can this part come off or do I need to clean it on the machine? It doesn't cause any problems but just bothers me.
Thanks for any advice you can give.

Try a little Hydrogen Peroxide with Dawn. Or rub a little window cleaner on a cloth. Could just be oil from your skin. If you have any hand sanitizer you could also try a little dab of that. If you have one of those magic erasers or a micro fabric cloth, just dampen it and see what happens.

I can't help with taking the part off but there should be a way to do it. Was the discoloration from the sun or heat from the machine? If the yellow goes all the way thru the only way I know to restore the color is to paint the part. If it's just oxidized from exposure to the sun then you can sand the color out. I've had best results wet sanding plastic parts by hand. Sanding by machine generates too much heat and can (will) melt and smear the plastic. Start with a fairly aggressive wet/dry sand paper around 120 to 150 grit until the yellow is gone. Work to finer grits, say something like 120, 180, 220, 320, 400, 600, 1000. The grits of sandpaper may vary. The idea is that after you get the yellow out you sand with each finer paper until all the scratches from the previous paper are gone. Don't skip grits. It just takes longer if you do. It get easier as you go. Wash the part and change your water with every grit too so grit from the previous paper doesn't scratch the part. After you're done sanding you can buff it out with automotive rubbing compound to restore the shine. The last plastic I sanded was an old saw handle from the late 50s or early 60s. It took a couple hours to do. It's not a fast process. The other choice is to paint the part. If the yellow goes all the way thru it might be your only choice.
Rodney

Thanks for posting this. I had saved the link for Retrobrite (the same thing) but the link is dead now. I've been meaning to try this.

Did you get it done? What did you use? I just bought a 158.10400 that has a yellowed tray.