Repair Pioneer PDR-509 CD Burner

Can anyone offer advice as to a likely problem with my burner? It will play music CDs without a problem, but balks at burning when I get as far as pressing the record button. I am using the correct disks that it is made to burn. All the circuitry and mechanical parts look to be in very good condition. I was able to get it to display an error code. When I attempt to record, towards the end of setting up to do that, it shows "repair" on the display.

Following the procedure to adjust focusing of the laser, I was not able to get it to show 01 F4 which is preliminary to adjusting focusing.