*Will Nulib unshrink a file which includes a Resource fork?
 
Newer versions (3.25 is the newest) will extract the data fork.
Older versions might not, but they should be able to list the contents
(nulib tv file.shk).
 
*Another possibility is that the snag was introduced in the
Apple-to-PC transfer. If your Apple II telecom program is set to send a
Binary II header (e.g. "Binary Up", etc. is set to ON), this could
produce a file which Nulib would view as 'messed up'. Make sure that
your Apple telecom program does not attach a Binary II header. Also, do
not ask ShrinkIt to attach a Binary II header at the time you create a
.SHK file.  
 
Also, NUlib v3.25 handles Binary II wrappers (and can identify them 
as such).