Dont shoot me for this... I let the model sit below a heater vent on each side. Rotating the loco every min or so while monitoring by trying to pull 1 side of the shell off. I used razor blades towards the front and rear nub to pry with till the shell popped up over both nubs.Question: how did you "warm the shell"....without damaging/melting it?
I have a gas furnace in the house. Air coming out of the vents is suppose to be around 110 degrees. So a short amount of time 6 inches away from the vent while carefully monitoring did the trick. Only took a few min to get it warm enough to flex and not crack.