My Panasonics of 2005-2007 manufacture function much better with DVD-R media.
As with any electronic device it is best to disconnect the AC cord for at least an hour or so before opening the case.
Servicing the DVD drive is a simple fifteen minute procedure on a DMR-ES15. One should exercise caution as the DVD drive is close to the power supply section found out in the open on the DMR-ES15 motherboard. Detailed cleaning procedures may be found in posts on this and other forums.
Today I replaced the largest electrolytic capacitor in the power supply of one of my DMR-ES15 models where I observed capacitor leakage when I serviced the DVD drive back in December.
Capacitor replacement requires disassembly to the extent of removing the chassis motherboard from the machine. Be sure to observe capacitor polarity before removing the old capacitor and soldering in the replacement capacitor. Different model Panasonics use electrolytic capacitors of different specification but all seem to be of the 105 degree maximum heat range.