Listen to your DVD Drive.
Does it make "clunking," "chugging" or "errrp" noises? If so, that's usually a dirty lens or a failed laser assembly. Other possibilities include a problematic Digital PCB or a damaged ribbon cable contact strip.
If the DVD Drive makes a "grinding" noise that's usually a dirty rubber hub. Clean the lens and rubber hub atop the spindle. The instructions are found in other threads, including:
Heat is an enemy to the fan-less DMR-ES15 if it has been closed up inside a cabinet or stacked with other heat producing equipment. There are any number of components that may have been compromised due to overheating.
The DMR-ES15 is an entry-level 2006 model, my first DMR-ES15 was purchased for around $150 in August 2006. That ES15 is now a standby recorder with more than 3,000 recording hours. A second ES15 is a standby recorder with around 1,100 recording hours. Two other ES15 models are now parts machines, one with a failed laser assembly and another is just plain "dead."
Perhaps it's time to consider a new Magnavox 2160 HDD/DVD Recorder, currently priced less than $200 at walmart.com. I own four of that outstanding Hard Disc Drive/DVD recorder model.