Ejector pins can’t return ,how can we do?

  Ejector pins are long pins that are used in the injection molding industry to push the final samples out of the mold. They are used forcefully to eject the solid part out of the mold and are usually made of high-quality steel.

The ejector pins push the final smaples out of the mold but if they can not return, how can we do?
 They must return befor mold closed. If they can not return that will crack and cavity of mold could be scratch, crack. And mass product can not continue.
Reason:
+ May be have trash on the ejector pins, oil and maintaining is bad.
+ Worker assembly ejector pins not good.
+ Angular pins were cracked when injection.
+ Resin were stuck in mold.
+ Temperature is difference between core, cavity, pin.
How could we do to solve the problem
  + May be have trash on the ejector pins, oil and maintaining is bad. You should clean the mould and add the lubricating oil.
  + If injection processing and you don't see pins or core crack, don't want stop injection, you can use cleaner. But i think your mold will NG faster.