Locking block comes reinforced on new M9 PTP's now. A new one from March 2009 had a defective External Cylinder Assembly. The bottom of the cylinder has a metal bar that pushes the bb up the ramp into the barrel. On this particular M9, the end of the bar fell off after the first 3 shots were fired. The bar was then too short to get the bb up the ramp without jamming.
This had to be a defect. The piece in question appears to be glued or soldered on to the rest of the bar. It is about 2-3mm long. The bar it is glued to had paint on the end so they did not get a good bond; the first few fully charged cycles rattled it free.
I never found the piece. I used epoxy to build up the bar that remained. Works 100% now.
Also have KWA M1911DS PTP. The cylinder seems the same and the little piece in question just appears to be glued on.