I experience the same thing. Try removing the door panels then lubricate the railings. It will help a bit. I don't think its the batteries coz dati when I changed my battery, ganun pa din. Its either kailangan na i-relay ang motor. Hmmm..baka defect ito ng Suzuki. Some of my other friends with Vitaras also experience the same thing. It can also be attributed siguro sa increase ng resistance ng mga wires as our rig ages.