DeskJet's "no status available"

I'm using an HP DeskJet 840C connected to the parallel port of a Fedora Core 5with cups-1.2.5-1, hpijs-1.6.6a-1.1, and hplip-1.6.6a-1.1.All packages are binaries from the Fedora repository.
The printer has been successfully installed using the hp:/ backend, andthe device URI in CUPS is hp:/par/DESKJET_840C?device=/dev/parport0. Thebuilt-in test page works, and CUPS can produce its test page -- however, allprintouts are unreadable due to what I presume are cartridge alignmentissues.
If I attempt to run hp-align, I get the following:

 HP Linux Imaging and Printing System (ver. 1.6.6a)
 Printer Cartridge Alignment Utility ver. 2.5
 ...
 Using device: hp:/par/DESKJET_810C?device=/dev/parport0
  [WARNING]: No status available for device.
 An alignment page will be printed.
 Please load plain paper into the printer. Press  to continue or
 'q' to quit.
   [ERROR]: Channel write error
 Traceback (most recent call last):
   ...
     raise Error(ERROR_DEVICE_IO_ERROR)
   base.g.Error: ('Device I/O error', 12)

The fix is:

  $ su
  $ cd /usr/share/hplip/data/xml
  $ gvim models.xml

Locate this section:

<model name="DESKJET_815C">

Change:

<io support="1" mode="0" control="0" mfp-mode="2" scan-port="0"/>

TO:

<io support="1" mode="1" control="0" mfp-mode="2" scan-port="0"/>

Also see here