1. power the printer
2. let your printer do its maintenance task (it does it all by itself)
3. please observe if the maintanance task finishes ok - green led indicating that the printer is ready.
4. open cover and observe if the carriage (the cartridge support) moves freely - it should stop after a while at the middle waiting for you to change cartridge (don't)
everything ok till now?
Thanks for your comments ... I gave up and bought a new HP 8500 Deskjet. I'm still curious about what was wrong, but traded in the 952C to get $50 off the new one. The problem started soon after I pulled paper out of the front (a no no!), so I imagine I did something to dislodge or damage the roller or paper guides.