My son has a Mintek 1720 portable DVD player that developed a "loading" problem with DVDs. They would never load, the display just kept saying "loading" forever. Therefore, they never played. However, it would play music CDs just fine. I went to the Mintekdigital.com website and saw that it posted this problem with the explanation that it was "defective." I called the tech support toll free number at Mintek (866-709-9500) and they told me exactly how to fix it! Thank you tech support person, Sarah! This might be the "adjustment" you were looking for even though your portable is not a Mintek brand. Okay, here is what you do. With the power turned off, open the lid and then open the hatch where you put the DVD into. Locate the laser lens and notice that the laser lens is attached to an assembly that moves diagonally outward in a slot. First, slide this assembly outward. Second, slide it back inward. Now repeat, slide out then back in. Next, put in a music CD and let it play all the way through. (This re-calibrates the laser head assembly movement.) When the music CD is done playing, put in a DVD, and amazingly, you'll have a working unit again. I just did this to my son's yesterday and I'm so happy! (One less thing I have to re-buy at Christmas this year!) Hope this works for you too!
Sue Kerslake, October 2005