In Edit Sketch
mode, select any sketch entity on Upper
Arm-1, drag the block close to Central
Arm-1, and then click 
.
Connect the central arm to the upper arm.
In Edit Sketch
mode, select any sketch entity on Upper
Arm-1, drag the block close to Central
Arm-1, and then click .
Click Zoom
to Area 
(View
toolbar), zoom in to the top of Central
Arm-1and the point on Upper Arm-1.
Press Esc to clear the view tool, select the point on Upper Arm-1, and drag it until it is coincident to the center of arc from Central Arm-1.
Save the model.
