I cut the side rail seal with a 6in1 painter/drywaller's tool, like a fancy putty knife with a paint roller cleaner halfround on the side, and a wide, edge sharp head, and a hammer. THe fsm shows a similar "special tool"...

THen I smack the side of the pan sump with a soft head hammer, or shield the metal with a piece of wood and smack that. It will pop loose.

Not responsible for advice not taken...