[philly0001]

I have an ICS M4 I am working with my stock upper gearbox. I have stripped a tooth on my piston and need to replace the piston. I have removed and disassembled the gearbox. I have the replacement piston but my challenge is how do I remove the piston head from the piston. I need to reuse the piston head so I dont want to damage it (unless I really have to, and if so how will this affect preformance). I have read that there is a cover on the front of the piston head covering the screw. There is a tiny hole (maybe a paper clip can fit in) on the cover and it looks like it is glued in, as I can not remove it. How can I remove the piston head? Would using something like nail polish remover help get the cover off or is it just going to ruin the piston head? Or is there something else that can be done. I am holding the nut down inside the piston shaft, so it appears the screw is turning in the casing and not unscrewing. Would it be best to just get a new piston head? If so does it come with the screws needed to attach to the piston? But I would rather not spend anymore money (and waiting for things kills me) since I might as well just buy a whole new upper gearbox at that point. Any help would be greatly appriciated. Thank you.