Replacement for crank mechanism for casement window

Hey Vince. This looks like the ROTO Short-Arm Operator, the 39-091. The handle that works with this newer version is the 39-224. Unfortunately, ROTO discontinued this assembly, and many of the parts it uses are no longer made. This includes that bracket arm that connects the short arm to the window sash. You will have to reuse your old one if possible. 

You also show the window hinge at the bottom of the window. This exact one is no longer made, but our 10" 36-004-10 might work as a substitute, so long as you replace the top hinge at the same as well. Take a look at the dimensions below and let me know if it matches well with the old window hinge. Let me know if you have further questions.

DImensions for 36-004-10

Sure, that looks like the link arm for the operator. You can disconnect it by using a slotted screwdriver (or any other similar tool you have) to push the detach clip back; that'd be the flat, "claw" shaped clip you see bracing the pin. Once the detach clip is pushed back, the arm will release from the pin and can be safely disconnected.