U can do the below steps but it will best if u call an engineer to the job:-
You see the access door in the back where you would remove a jam? That is the back side of the fuser unit. You'll have to take the scanner top off and the other back panels to unplug the scanner and controls....the sides, the laser assembly, other things... and finally you'll have to disassemble the fuser in order to remove it and get access to the sensor arm.
Just look and remember where all the parts go
You can't just remove the broken sensor arm. The printer needs it to know where the paper is during its travel. It will need to be fixed or 'engineered' back to a functioning form.Good Luck...