Question: If the jaw cannot be activated because the trigger is not able to keep it in 'open mode', can I then change the trigger?
Answer: Yes, if the trigger is worn down or even broken, then it can be changed. You can buy a package of 10 triggers and if you use a torx screwdriver it is easily replaced. Takes about 2 min.
But first you should check if the trap might just in need a good cleaning. We often see triggers working again after a wash and a brush.