direct pull cantilever brake service
 

Is there any information on dissassembly, lube, assembly of these brakes? I went to the Sheldon Brown site and he only talks about adjustment.
The problem I have is mine always get sluggish. When I release the brakes the levers are slow to spring back to their at-rest position. Right now I have one brake arm that doesn't spring all the way back and the pad contacts the rim when the brake is not applied, causing drag.
TIA

Could be bad cable/housing. Possibly not enough grease between the calipers and bosses on fork/stays