Top Rack roller spindles disengage.

Without removing runners, with pliers opened up bottom of runner channels and popped out bottom first the front stops. Then removed the old rollers, installed the two new front roller/spindle assemblies, replaced front stops, squeezed channels back to original shape with pliers. Pried off old spindle mounts on rack, lined up rack with new spindle/roller assemblies and pushed home with screwdriver. Rear roller/spindle assemblies did not need replacing.