lasers get weak, based on hours used. some units have complete replacement head assemblies like my used one does. Some get dust on the laser surface, a cleaning solves it. I have used one of these for many years, my and friends units. fixed some, not others, definitely worth a try https://www.amazon.com/Cd-And-Dvd-Lens-Cleaner/dp/B000HI63Z6/ref=asc_df_B000HI63Z6/?tag=hyprod-20&linkCode=df0&hvadid=167141218295&hvpos=&hvnetw=g&hvrand=15085921044906296673&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003512&hvtargid=pla-307958041849&psc=1
here's the head replacement unit for mine