Blade hinge assembly.
(Was formally part number DK510)
It is important to ensure the two thin metal hair springs (see red arrows) are both correctly seated in the small pin sized holes on the right and left hand sides of the latch assembly.
These springs are essential to the latch release of the blade working correctly.
Customers may consider it prudent to renew the latch assemble when re-placing the old hinge assembly.
See parts diagram – item 42