2002 Chevrolet Silverado, automatic transmission(4L60E), 36,091miles.
About 4 weeks ago my tranny would make a knocking noise everytime it shifted to the next gear until recently when I stopped at a stop sign and began to take off the transmission made a loud grinding noise. I inspected the tranny and everything seemed to be fine. The fluid was also good. After that happened I now have no reverse and I think 2nd and 4th gears are gone too. The tranny also makes a buzzing noise in park, reverse, and neutral. I've been told to drain the fluid and change the filter. I did so but it is still the same. I've also been told that a broken sun gear shell may be causing the problem? But I can't seem to locate it. Does anybody have any other suggestions on what the problem may be? Your help will be greatly appreciated.