Remove the bottom, remove the main circuit board and found the pin motherboard connector cn1301 off the first leg, and has been bent, not inserted to handle phone circuit board under the seat. The first leg of the pin and straighten it with the rest of the hot melt adhesive 8-core pin aligned cement (next cn1301 two square holes, with a lamp sighting of these two holes can be clearly observed cn1301 is plugged good). Plugged cn1301, installed the main circuit board and backplane, there is no longer a paper jam error when copying the boot, but a copy is still black. Press the panel "function" key, then press the "Select" button, select "report" (report), print out the contents of the still black. According to the scanning head cis copying has issued a yellow green, indicating that cis intact; thereby determining the recording head (tph) is damaged, replace the recording head, the machine is working properly, troubleshooting.