Hi Avi, I have read elsewhere that some of the gamo trigger bloks are a bitch to get out. Almost like they were hammered in.. Try tapping it from the front with a wooden mallet.. 1st remove the beartrap off course else you may bend it
Seem to remember I had to remove the spring first as the trigger assembly caught on the plastic spring stop, but could be put back with the spring in place.
Sure one of the Gamo fundis on here could help you though. Failing that resort to the hammer method.
All the best