3D print error

[Nickrpb]

Hi Guys I’m relatively new to sketch up and 3d printing

im trying to print a simple screws on a shaft.

but the part of the flight that connects to the shaft is not printing

I’ve done explode and intersect with selection

please help.

Im using Cura as my slicer

This is the drawing

this is in Cura with the holes indicated

thanks for your help this has been driving me mad for 3 days