There is technically no "recalibrating" the potentiometer. What it amounts to is lowering the threshold on the laser. What this will do is allow you to play your games but will burn out the laser far quicker. When you make these kind of adjustment you must do so in very small increments. Larger turns will just render the unit unusable.
The laser is going bad. Mine has the very same issue. They can be purchased from Ebay for around $25.
25 for the laser replacement itself or another dreamcast?
It's actually both.
At this point, instead of buying a replacement laser, I would buy a replacement DC. Keep the broken one. And as a hobby repair it one day. The dreamcast is way undervalued and a system can be purchased for less than replacement parts.
But do at some point learn to replace the laser. The GD Rom laser can be much more difficult to replace than the SEGA CD or Saturn lasers. And most of the time the lasers are not really new. They are usually salvaged from Dreamcasts or Naomi GR-ROMs.
Personally, I am hoarding Dreamcasts and Saturns (I don't actually have many at this point). But If I find a DC in good condition for under 20, I buy it. If I find a Saturn in good condition for under 30, I buy it. My main units are still in perfect working order (my saturn I just got used a couple of months ago but my dreamcast is my original 9/9/99 unit). But I do know that lasers die. Just the way it is.
