As Super says, it entirely depends on which engine you select, as there are many ways in which the face is fixed on.
I'm in the process of detailing Salty, of which more in due course. The front (black & yellow striped) part just screws off, and it looks from the inside as if the face is just fixed on by three plastic studs that have been melted on their ends, but having drilled those out I found that there had been a generous dose of solvent glue used as well. In the end I had to cut the face out from the inside using a saw-disc on a rotary drill tool, which worked well but might not be an ideal introduction for the inexperienced or faint-hearted.
I'm in the process of detailing Salty, of which more in due course. The front (black & yellow striped) part just screws off, and it looks from the inside as if the face is just fixed on by three plastic studs that have been melted on their ends, but having drilled those out I found that there had been a generous dose of solvent glue used as well. In the end I had to cut the face out from the inside using a saw-disc on a rotary drill tool, which worked well but might not be an ideal introduction for the inexperienced or faint-hearted.