apparently the owner didn't use it much and it looks pretty much new, aside from the loads of dust it collected. i'm charging it right now and at first, the smart charger was blinking yellow (meaning battery or charging failure) then i unplugged the charger and plugged it back in... now the charger's yellow, while the tennis tutor battery indicator is red. Can someone give me a run down of the battery indicator meanings? I dont have a manual. Also, should i not waste time and buy some replacement batteries? what are the chances of my smart charger being broken? summary: tt indicator = RED charger indicator = YELLOW sometimes it's tt indicator = RED charger indicator = blinking YELLOW actually i DONT have the smart charger below: i guess i have an older model, but it does say "smart charger" on it.