Printer has fault code E:0441 on start up.  I have tried COLD RESET,
it produced only the same fault.
I have removed and put back ink cartridges and printheads.  No improvement.
I tried COL RESET again.
HP service tell
me that the printer must be returned to be repaired.  
What causes this fault and what can I do to fix it myself?

I work for epson tech support. I know if its out of my league but if
HP tell you that this error code needs repair, that is something to
check for.
But here are a few things that you can check for 

- Obstructions that may prevent the path of the carriage
- Try diffrent cartridges (some cartridges can be defective, if you
just replaced them)
- Try a rom reset if applicable
- Plug the printer directly to the wall (not in a power bar)

but if these hints doesnt do the trick, there might be a part inside
the printer that broke, or when you do head cleanings, inside the
printer there is a ink reservoir, make sure thats empty.  Sometimes it
can be full and will cause and servicing error..

Hope this info helps you.