Large Scale Central

MTH Big Boy Tender - How to remove shell

I just acquired a recent issue MTH Big Boy (70-3048-1) and want to open up the tender shell to explore how to convert to battery power. The manual says to remove 4 screws (2 at each end). I did that and the shell at each end comes up but it acts like it is still attached in the middle. I wonder if there is a tab or something and how to get it to release. I have been hesitant to force it so as to not damage the shell.