My 1984 190e Mercedes has a serious transmission problem. I can achieve first gear, reverse, neutral, and park. However, the car won't shift out of first and into second while in Drive. I was told the transmission was shot, so I ordered a new one. This transmission experienced the exact same problem. First gear and reverse only. The replacement transmission sent to me also had the same problems. I am beginning to believe it isn't the transmission itself. What electrical component causes the transmission to actually shift gears while in Drive? And/or what else would cause this perplexing problem? Please HELP!