Lisp to change wblock from 2004 to V2000.Please help

Hello,
I am trying to wblock out part of a drawing and have a routine which
automatically resaves the file as V2000. Surely this can not be hard
but as I have limited lisp skills I am stuck. Any help would be great.

(if (findfile dwgnm)
(command "wblock" dwgnm "y" "" '(0 0 0) ss "" "oops")
(command "wblock" dwgnm "" '(0 0 0) ss "" "oops")
(command "filedia" "0")
(if (findfile dwgnm)
(progn (command "qsave")(command "open" dwgnm))
)

(COMMAND "saveas" "2000" dwgnm "y")
(command "filedia" "1")
)

This obiously does not work as the drawing will not open as I can not
work out the syntax...



Thanks
Mike Nowson

PS I would rather not have to close the current drawing that I am
wblocking from is that possible. Ie to open another file without
closing the active file?