Knickerbocker was a name used on guns manufactured by Crescent Firearms for Montgomery Ward from 1915 to 1925. Before 1915 it was a house brand for H.D. Folsom. Crescent also imported many guns from Europe and sold them under the Crescent name. They would also put any name you wanted on the guns for the price of the stamp. There are over 200 different brand names used on these guns.
Numrich has a parts drawing, but no schematic. There are no schematics available for the Crescent guns, but all sidelocks are similar. I have uploaded a sideplate "schematic" (picture) for a hammerless gun that may help you.
If your gun is a hammer gun I can take pictures of the one I am working on in the morning and attach them for you.
The entire page uploaded, the top right has the assembled sideplate.