It sounds as if you've probably got badly worn keys.  Many times a correctly
cut new key (not a duplicate of what you have) will solve the problem along
with a little lubrication.  Lock wear is seldom an issue as the Vanagon
locks are quite robust.  All the locks can generally be serviced and rebuilt
if necessary, with replacement not necessary.  If a lock does require
replacement, it can be rekeyed to match the existing system.  Feel free to
contact us directly if we can answer your questions.
Steve Sandlin, Registered Locksmith
Steve's Lock Shoppe
http://www.steveslockshop.com
'84 wolfsburg Westy
'79 Bus
'00 New Beetle