This is a follow-up to my earlier post.
I am assuming that you misidentified the model number of your Panasonic DVD/Hard Drive recorder. The DMR-E55 is a 2004 model DVD recorder without hard drive. The DMR-EH55 is a 2006 model DVD/Hard Drive recorder. The serial number label will indicate either the month/year or just the year of manufacture (where the first number in the serial number sequence indicates the year of manufacture).
Since Panasonic no longer lists the parts numbers of DVD drives or DVD drive controller circuit boards on their website it is no longer so easy to determine compatibility should you need to replace your DVD drive or its controller circuit board.
I have examined the DVD drives and controller boards on two of my 2006 models, a DMR-ES15 DVR and a DMR-ES35V combo recorder. For a time Panasonic listed DVD drive part numbers on their website. These models used DVD drives with the same part number. While the DVD drives I examined do not share any externally stamped numbers they appear to be identical. Both of these models use the same DVD drive controller board, part number VEP79132. The controller board is located under the DVD drive on the DMR-ES35V and beside the DVD drive on the DMR-ES15.
The fact that two Panasonic 2006 models use the same DVD drive may indicate that the same DVD drive is used on other 2006 models as well. But common parts shared by these models does not necessarily indicate that these parts may be interchanged with those on your DMR-EH55.
In any event the Panasonic Service Center will give you information concerning warranty or non-warranty repair for your DMR-EH55.