Popular science 1943, Mortite is a very porous non synthetic made from minerals, used to make plastic injection molds because nothing sticks to it. This substance can be rolled out flat and used as a deadening material to fight resonance on ineffective turntable pilths but not the internals of electrical equipment.
The only possible way to remove this compound is to remove the top cover and stuff with absorbent rags, place a large baking pan under the receiver that can hold liquid.
Keep absorbent rags wet with mineral spirits.....found at the hardware store !!!!
The idea is that Mortite is a mineral compound and in its original state contained mineral spirits and once the mineral spirits evaporated the main ingredient titanium hardened up.
You....or your friend are going to have to constantly check back on the evaporation rate of the mineral spirits to keep the absorbent rags wet.....like right before you go to sleep, because if the rags dry out your back to square one.
This is old school technology so this process will take a long time....
After the Mortite becomes a putty, I’d use a pressure washer to remove the majority then follow up with mineral spirits to remove the residue.
Good luck.....
