Try this step by step procedure and see if you go any better than before.
- Open the 14031 CCad.dwg
- Assign Co-ordinate System – MGA-56
- Type mapimport into the commandline
- Change the file type to Mapinfo TAB at the bottom and then select the contours.tab
- Under the DATA heading, select the create object data, then click on Select Fields (make sure you tick on add unique key field)
- Then make sure the Input Coordinate is set to Lat/Long (LL-GDA94), tick on import polygons as closed polylines and click OK
- Save the drawing and get out of it.
- Start a new drawing from your DWT and save the drawing
- Type mapwspace
- Click on Map Explorer
- Right click on drawings at the top and attached the drawing you just saved and got out of
- Then right click on Current Query and select define
- Click on property and then select layer and ok
- From the query mode select DRAW
- Then click on Alter Properties and select Elevation
- Go down to expression and click on it
- Click on Object data expand out contours and select Elevation and click ok. Click on the add button where the expression has been added, the elevation details will show up the top and then Click OK
- Then click on execute query
- Click on cancel when asked for a shape file
- List one of the contours in the drawing and it should have a z value on it now.
Let me know how you go.