(How ) do you clean your machines after use

I just finished the injection-machine and after using it for the first time I left the plunger in the top part of the barrel and let it cool down. Then it was stuck because the leftovers of the PP were still on it and that got solid.
Next time I heated the machine, but it didn’t move because the top part of the barrel doesnt get as hot as the rest of the barrel.

How does do you guys do this?

I added a heater to the top of the tube and moved the temp sensor below the hopper.