"The case which contains the planetary gears"- - - -would you by chance be referring to the "internal gear" the one with gear teeth on the inside diameter? If so, yes it should be a dark gray or black color. It's hardened to the same degree as the planet gears, so they don't wear each other out. I don't like your description of the drum the rear band rides on. That doesn't sound right. You've got something going on that's more severe than a simple incorrect arrangement of parts, so it's going to be necessary for someone who is very familiar with that transmission to do a full teardown and inspection, all the way to disassembly of the clutches, pistons and all, and an inspection of every seal. I'm going to need to refresh my memory on the power flow in 1st. and 2nd. gear to give you an educated guess about what's slipping and/or failing to engage. I strongly suspect your "rebuilder" has made some expensive errors during assembly unless the transmission was actually run and badly abused for a short time after it was rebuilt.
Jerry
