Better still, don't soak them, take them apart and clean them properly. It's not difficult.
Definitely. You can use something like WD40 for cleaning (Kontakt 60, a spray for cleaning electric contacts, is also useful - it removes dirt very well and even some rust), provided that you swab the agent completely, the surfaces should be dry (shutter blades are designed to work dry rather than lubricated). A few days ago I did so with a sticky, old Compur #2, it took about 15 minutes + an hour to find a way how to access the blades.