I don't have photos yet, but there are four notches (two on each side of the tender shell) that hold the shell on.
1. There is a tall nearly full length grab on each rear corner. You'll need to carefully pull the bottom connection point for that grab out (it is attached to the bottom half of the tender) before you can remove the shell.
2. I then turned the unit over and carefully took four toothpicks and carefully inserted them about a centimeter in from each corner between the shell and the bottom of the tender. Be careful with all that piping.
3. I could see that all four of the little molded in tabs in the shell were visible next to the toothpicks which meant the shell should come off easily. It still require a bit of wiggling of the trucks and bottom half of the tender to get it free. It is stubborn.
Once it is off double check to make sure the long grabs at each corner are still attached to the upper shell as they could work loose. After that, installing the decoder is just a matter of carefully prying off the stock circuit board and replacing it with the new DCC decoder you bought. The shell will pop back on with a little bit of force when you are done.
-jamie
