Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, how long has the Panasonic DMR-EZ28 been in use please? And would you say that the recording function has been used rather often?
The described symptom, what has been tried (cleaning) and taking into account the age of the unit as well as its usage would almost always point to a weakening / about to fail laser reader, the optical pickup.
The prescribed approach is repairs; i.e. replacement of the traverse ass'y or at least the optical pickup.
The Service Manual prescribes a test on how to determine if the laser indeed has gone bad and therefore would confirm that repairs are needed.
Would excerpts from the Service Manual on how to perform this test serve your need then?
The test would have to be done while inside the Service Mode. Please click HERE on the procedure to enter Service Mode.
Inside the Service Mode, the procedures HERE would allow tests on the laser.
Again, this is a test to confirm laser functionality.
This confirms an internal hardware issue.
If comfortably able and feel safe to do so, are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even a soldering iron?
Great on the DIY!
As new, the DVD drive P/N VXY2010 is NLA (no longer available) even from Panasonic/Encompass. Please click HERE. A potential source for a refurbished part is HERE but currently is out of stock.
A hopeful alternative is to have a 3rd party perform the "surgery" and just replace the laser of the DVD drive.
Please post back how you would want to approach this and/or should additional information be needed.