bookmark+ help required

[Guido Van Hoecke]

Hi,

I switched to bookmark+ and some of my bookmarks now have a different
format:

Old format:
#1=(#("past.org" 0 8
      (bmkp-full-record #1#))
    (filename . "~/org/past.org")
    (front-context-string . "* DONE <2013-04-")
    (rear-context-string)
    (position . 1))

New format:
#1=(#("agenda.org" 0 10
      (bmkp-full-record #1#))
    (end-position . 12206)
    (time 21790 27563 50717 0)
    (visits . 0)
    (filename . "~/org/agenda.org")
    (front-context-string . "* TODO <2013-05-")
    (rear-context-string . "g niet gestart!\n")
    (position . 12206))

I have an eshell function that allows me to type `j bookmark` (got it
from http://www.emacswiki.org/emacs/EshellBmk (thanks!)) and it fails
with the new format: it expects the 'filename' cell up front in the
record. That works with the old records, but not the new ones. In the
above 'agenda.org' bookmark it thinks that the filename is '12206'.

Here's the relevant code:
  (if (setq filename (cdr (car (bookmark-get-bookmark-record bookmark))))
  
My lisp is not up to turning this into an expression that would
correctly load the filename from old formats as well as from the newer
format.

Any help and suggestion would be most welcome and appreciated.

TIA,

Guido

Note: I am very willing to update the wiki with proposed working
solution and give due credit to you guys.