Your description points to a dirty lens or a failed laser assembly. Did you also clean the lens? If the "no read" situation persists there may have been some disturbance to the ribbon cables or there might be a problem with the DVD Drive's on-board controller board or the Digital PCB itself.
With the disc tray extended or removed there will be specific procedures required for reassembly/realignment of the DVD Drive. This post has a link to the first of two AVS posts describing the procedures for 2006 and newer model Panasonic drives:
DVD Drive realignment/reassembly procedures for earlier models may differ in some respects.
Panasonic's corporate Service Center in Elgin Illinois continues to offer the $130 flat-rate repair for Panasonic hard drive recorders. Current information is found here: