hp 3330 "door open or no print cartridge error"

[edgar]

I was given this printer in quite a few pieces. The owner installed a fuser assembly on it, don't know why!! He could not put it back together and I did it for him. I get an error mesage "door open or no print cartridge". The door is not open and there is a cartridge in it. I have tried other cartridges and the problem persists. Any ideas why this is happening or what I can try next? I read on a forum that a c301 switch may cause this problem but could not locate the switch in the machine. Any help would be much appreciated.

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