Sorry for my delayed response, watching the grand kids always makes for an interesting day.  I would like to thank everyone for their quick response to my questions. I'm very glad to hear that this power pack is functioning correctly. The power packs I have used did not have these features and without the user manual I was in unfamiliar territory.
Again,  thanks to all for your help answering my questions, this is a great forum.

Hello everyone, this is my first post:
I was given an (Transformer /Controller) a Bachman Spectrum Magnum Premier #44-6683 to use with my grand children's Thomas the train, their transformer just died.
I called Bachman and they do not have a copy of the user manual for this product, it is to old, and no one in the service department remembers the functions of this product either.
If anyone can help me understand how these 2 button's should function, the "Momentum" and "Brake".
What I have noticed while using these buttons:
Brake button:  while depressing and holding the brake button in the engine slows and comes to a full stop, when I release the brake button the engine will go back up to its original selected dial speed.  It would be nice to know if this is the normal function of the brake button. 
Momentum button:  Pressing the momentum in till the red LED above it is on,  then selecting a dial speed of 60 a 20 seconds wait time till the engine slowly starts up and builds up to a constant speed. If a lower dial speed of 40 is selected an even longer wait time of 35 seconds till the engine starts up,  and if a dial speed of 25 is selected a 50 second wait time till the engine starts up, and so on.
It would also be really nice to know if this is the normal function of the momentum button for this Transformer/Controller?
Any help with this issue would be greatly appreciated. Thank you.