HELP! Definitive process for liquid peroxide treatment needed

[Telephones_etc]

(I wasn't quite sure which thread to post this on so apologies if it's misplaced)

I just bought a blue (turquoise, light/baby blue?) WE Trimline on eBay for $17, and it's going to need some serious discoloration treatment. I've never taken on this sort of project and there seems to be a lot on the subject (i.e. www.classicrotaryphones.com/forum/index.php?board=23.0) but I haven't found a definitive how-to for liquid peroxide discoloration treatment. Specifically, "Salon Care 20 Volume Clear Developer". Could someone please provide a step-by-step instruction for how to do this? It would be much appreciated

The specimen:
https://www.ebay.com/itm/264590960531    ( dead link 02-17-21 )

The treatment:
https://www.google.com/shopping/product/12440628159956875376

[Jim Stettler]

Could someone please provide a step-by-step instruction for how to do this? It would be much appreciated

I would like to see step-by-step instructions as well.

Does anyone know the long term effects on the plastics when you use peroxide or retrobrite.
According to this article, it makes the plastic better.
https://www.heypoorplayer.com/2016/03/30/how-to-whiten-your-old-consoles-with-retrobrite-gel/

That would be really cool if it does. It sounds kinda iffy to me.
If someone that knows chemistry would like to comment on this subject, that would be great.
Jim