Can't answer your question as to why your appliance smokes. With regard to the question of oiling the Chef, I have an old booklet that says "The gearbox of your Chef is permanently packed with grease and no additional lubrication is necessary during its normal life".
Now we come to the "green button". Some mixers are fitted with an overload protection device. My booklet says that where this is fitted the mixer " . . . will stop automatically if overloaded. If this happens switch off, raise the mixer head to expose the green button. Allow the mixer to stand for a few minutes then press the button so mixing can continue."
My mixer is about 10 years old and gives the following information under SERVICE:
For any repaires in or out of guarantee, servicing or selected spare parts, please contact your Kenwood Authorised Repairer in Yellow Pages under the Electrical Appliance Repairers section or Telephone (0705) 476000 extension 2800 Service Department.
Don't know whether this telephone number still exists (I have a feeling that the code, at the very least, will have changed).
Whenever I have wanted spares or someone to repair an appliance that is out of warranty, I have usually found that the John Lewis Partnership stores are very helpful as they keep a list of spares suppliers etc.
Sorry this answer is so very late after you posted your question (I know it's not all that helpful, either), but I have only just come across this site to-day.
BeBe
July 2006
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix blenders/mixers.