no,i dont think it will damage it.
heres what I do (did) when i gunked one of my folders up.
turn on the hot water spigot and let it get HOT!,as hot as it will go...after its hot,flush it with the hot water,getting as much of that gunk out as you can. After its out,the hot water (in theory) should evaporate,due to its own heat.
after its had a little while to evaporate put some kind of lube in there (my favorite is tuf-glide) and work the action several times,to spread the lube out.
WD40 does have a place,IMHO in cleaning knives,but not as lubrication.
-mo.