I want to modify my PDR GT+ by adding silicone through butt cap. I believe mine has a trap-door. Is there an easy way to open it? Please advise. Of course, I can always take it off completely and do it that way.
If it has a trapdoor, you'd see a small hole next to it. You can put something in it and use it as a lever to open it (like a bent paperclip or a very small screwdriver)
