Photosmart P1000 HP78 reset

I'm trying to resolve the 'colour cartridge not compatible' message and amber light
flashing on a Photosmart P1000 which was recently donated to our group. I presume this
message is telling me the print count is currently up on the HP78 colour cartridge in the
printer.

I've tried the various recommended procedures for resetting, by following each of the
suggested sequences of covering and uncovering selected contacts on the cartridges,
all to no avail.

Does anyone know what the state of the art is in resetting the cartridges used in this
printer - the 45 and 78 for colour - particularly as it pertains to the P1000? Does the
three cart. trick work? We're not prepared to lay out the extra investment merely on spec.
Have HP superseded the two-id memory in the firmware, or is a 'spent' state written to
the cartridge chip when the print count is up?

Any suggestions would be welcome.