When the canopy is removed from the lamp, lift the broken support off. The wires should now be accessible from the top.

Save these pieces, as they might be useful in reassembly.

This old lamp had crimp on wire nuts, which I cut out with wire cutters.

Mark the positive wire on the main power cord; this can be done with a marker, tape, or most any other method.

The main power cord will usually be the same color as the lamp, but can be identified by white wires on the light fixtures.

Remove the small cover at the base and save it for reassembly.