I ran into (what seems to be a common issue) of a hard rack, and a slide not returning to full battery. After checking a few options- I replaced the guide rod- the only after market I could find on a Stainless Steel rod and spring was StainlessSteelGuideRods.
They have their own site and are also on Amazon.
RESULT: It was magic- terrific upgrade and the Stainless has a longer life that the stock guide rods. They are one piece and don't have the slight bend that the stock rods develop. That issue causes both problems I had.
PRICE: I found the .40 slide for the shield among the more expensive ones that they offer- but it was a $40 fix and $4.50 shipping which was well worth the fix. It's a drop in ready and literally was done in a minute.- I highly recommend the upgrade if you are exhibiting either or both of those issues with this weapon.