@A Smug Dill, I'd be interested to know whether the M4 x 0.6mm screws will fit into the 3008 without needing to be filed back:
Some in the packet of sixty I bought work just fine out of the bag, while others took a tiny bit of filing down (which I did quickly with a nail file because it was within reach at the time) by maybe 0.1–0.3mm. Easy peasy.
Using those screws to replace the metal screws (exactly the same size as that in the Wing Sung 3008) inside the caps of Delike New Moon 3 pens was a different story. One worked just fine. In the second pen, there was glue in the threads of the metal screw put in place at the factory, and my plastic M4*6mm replacement screw just wouldn't hold properly and then broke in two. Trying to remove the broken end of the plastic screw from the filial was a royal pain. Tried a second plastic screw in that pen, and it still wouldn't hold properly, so I had to give up and put the metal screw back (after coating it with silicon grease).
I can easily spare eight or so screws from my packet of five dozen, if you prefer not to wait a month to to two months for something you order on eBay to arrive from China. Just let me know in Private Mesaage here how many you need and what your address is, and I'll send them to you by regular Australia Post letter mail at my cost if you like.