It seems strange that the plastic blade is a professional job that was made in moulds, It has the same two adjustment screws that the normal ones have too!! (Deffo not home made as there are collapsable mould lines on it )
HERE's another pic of the whole of the disassembled trigger unit
It seems original to the gun to me as it fitted perfectly and worked even though the pivot hole was snapped through! I had tried glueing the broken parts together in this pic but the glue didn't hold
John