Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
When a roller in the fuser has been damaged in anything like the fashion you describe, there are two approaches to fixing it:
1. the minimalist approach, where you only replace that one roller that was damaged, and have to disassemble the fuser and then reassemble it afterwards, as well as getting the fuser assembly out of the machine and putting it back in, in order to replace the roller.
2. the standard approach: since there may be other problems (such as, a tendency to overheat in the whole fuser, in your case), one replaces the whole fuser assembly.
In a Brother MFC-9340CDW model printer, the fuser unit is replaceable from this standard-enough supplier:
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