Bleach or Milton and soak in vinegar. Carrots and beetroot contain very strong colour dyes and will immediately cause discolouration of the front-end parts of your Oscar juicer. You will also notice that after some time there will be a chalky build-up on the parts to a greater or lesser extent depending on how well the parts are cleaned. This build-up is similar to the build-up you find in your kettle. On your Oscar juicer the build-up is caused by the calcium found in fruit and vegetables that you juice.
Can this discolouration and residue be removed? The only way to reduce the dye on the parts is to soak them in Milton or Jik. Now I know that for most of you this would be a distasteful idea and I would agree. Since I know that the colour is purely an aesthetic issue, it would not bother me. Guess you have to choose which you dislike the most – discolouration or bleach.
Now regarding the build-up of residue on the parts. This can be sorted out fairly quickly and kept under control. Put a cup of the cheap spirit vinegar into about 2 litres of hot tap water and soak the parts that have the build-up on overnight. Rinse them off and brush off any residue left in crevices of the juicing strainer.