When it is cold , like now in winter ( 40 to 55F in my area). I do a cold start in the morning or night and give it at least 2 minutes idling to warm up the engine until the temp needle is in the top of the red band. From Park (330ci ZHP Automatic Transmission with 240k miles) to Reverse, some times I don't really hear thus feel the gears engaging in the back of the car and after I give it some gas(to 1700 rpm), it will reverse(in R) or drive forward(in D) slightly for about 5 feet and stop or not move further. The car just stays there even if I change gear to P, R, D, P , D several times.. I would not attempt to rev it pass 2,000 to avoid hitting something unexpectedly. I would have to turn off the engine from where I am safely, then turn the engine back on( on and off several times if needed) and try to change gear . Once I hear the thud sound of the gears changed, then I give it some gas to rev up the rpm so then it moves\drives like normal on that instances. From what I've ready online, it looks like I should change the transmission fluid first. I did see the notes from back in Feb 2023 that my indy shop said I have a leak and that I needed to replace the selector rod\shaft seal located on the left side of the transmission for like $300. Are these two things to do first, a good start? As long as I don't have to replace the transmission or its auxiliary unit, I'm fine to give it a try. It was 100k miles ago that I had the transmission fluid changed and transmission is believed to be original.