Hello my name is***** look forward to assisting and am very sorry to hear that you are having this problem. The imaging unit would not have caused something like this though the fuser normally will. Since that has already been replaced the problem is normally either the thermistor or the halogen lamp. You would need a technician to replace either. It sounds like you have a low or open heat error since it never warms up fully or gets to hot, see this page for an explanation of what can cause this from the service manual: Click Here If you have any questions at all click on reply to expert and let me know. If not please don’t forget to leave a positive rating for my help - it is greatly appreciated. Please note you are rating me only not this site or your Xerox.