See this post for more disassembly/assembly information and a photo showing the correct far left positioning of the DVD drive roller/slider at the rear of the disc tray before reinstalling the DVD drive lid.
If your Panasonic has the black plastic DVD drive, the DVD drive lid anchors at the rear and lifts at the front. There is little clearance at the front with those black plastic DVD drives. You may have to remove the Panasonic’s front panel to allow removing the DVD drive lid. (The photo shows a newer metal DVD drive.)
When fitting the front panel back to the case on VHS models, the VHS door must be held open to align the VHS door lifting mechanism.