My '99 E430 with the electronic key, does not engage the starter immediately on occasion. It sometimes requires me to hold the key in the start position for up to 8 seconds before the starter cranks. When it does crank it is strong and starting is immediate. I have checked the battery voltage in the key; it seems normal (3.1v). I thought it could be the starter's brushes, but the car is only 4 years old. The problem occurs irrespective of engine or outside temperature. Anyone have any insight or suggestions?