How to lube Carb diaphram?

I have a stuck vacuum piston in my motorcycle's carb which is causing only one cylinder to run.



When I pulled apart the carb and cleaned it (yes I removed all rubber/plastic parts), I noticed this piston was stuck. I smeared what lube was left on it around and tried to coat it, but it didn't work.



What type of lube am I supposed to use on this?



Can I just remove the air intake and spray some WD40 and work it around without removing the carbs again?



Thanks!



Specs:

1998 Honda Shadow vt1100



Heres the diagram link (Carb Comp.): http://www.bikebandit.com/houseofmotorcy鈥?/a>



I'm talking about part #16 in that diagram.How to lube Carb diaphram?
try penetrant like knockerloose or kroilHow to lube Carb diaphram?
The reason it could get siezed is because it may be dirty or have gunk built up in the carburator. Try running some Seafoam engine cleaner through the system. Seafoam might work better than WD40 because it will completly clean your carburator and engine. Run some through the intake and some in the fuel tank as well.



http://www.seafoamsales.com/motor-treatm鈥?/a>