I thought I would add my two cents on this. After recapping this latest Duo I acquired, I was getting cd audio cut outs, laser whine, etc. Looking over the gears, they did have the tiniest bits of plastic crud built up, which was causing the gears to jam while I was testing. I stripped the gears of all grease, and cleaned the gear teeth with a tooth brush, then re-lubed everything. After all of this I had the nasty whine still, and also, random audio cut outs. I noticed the whine got worse, as did the audio cut outs, the further down the disc the laser had to read. The makes sense, as the laser has to bob and adjust focus more the further down it reads due to disc warping and spin rate adjustments, etc, and not being calibrated right will cause it to lose focus during its eye bobbing up and down.
Unfortunately I don't have a normal pressed music cd that can go the full 80 mins, but I did have a Star Wars Return of the Jedi 2 disc soundtrack set, which happens to have both disc clock in at over 70 mins at least, which I was able to use for helping with adjustments.
Adjustment to any of the pots on the TurboDuo's gave no positive results what so ever. In the end it amounted to me needing to simply adjust the pot on the laser itself. I would play a track or two, if whine persisted, shut down, adjust the pot a tad, turn the unit back on, and test again on the same tracks. No whine, good, no skipping, even better. Move on to the next couple of tracks, rinse and repeat. Eventually I got the whine gone completely from this cd set, and all games mainly except one. It was still present during Image Fight II, especially during the last stage music track, which I would get whine and music cut outs. Due to this, it still needed some slight adjustment still.
Once the laser whine was eliminated from this, it seems everything was about as perfect as can be. No more audio cut outs during the stages music play back (by now it should be no surprise why I beat Image Fight II, I was using it to calibrate the laser, causing me to play the game over and over and over again). As is, everything seems good to go. I dont play cd-rs on old hardware, so I cant comment on how well they would play back, but so far every cd game I own has been going strong since final adjustments.
Some recommendations I would suggest off hand that I know could be helpful in thorough laser adjustment is the following:
Image Fight II (you can pause the game during gameplay and the music will continue to play, and loop, so it helps to let it sit and loop a track for a good 20-30 mins so you know it can play it without skipping/cutting out)
any pressed music cd that meets or passes the 72 min mark
random games that you can get to play to near the end of the disc music wise (Winds of Thunder/Lords of Thunder is a good candidate for this with its audio tracks being accessible from the option screen and its 19th track being near the end of the disc)
After all of that, its good to just do general gameplay testing. You might run into a oddball game that wasn't pressed as perfect as it could have been, so it might cause a skip or something, making you pop the system back open for a last calibration. The more titles you try out after general calibration, the better off you will be.
Anyway, like I said, just my two cents based on the recent experience. This was not a issue I had run into before with other systems on laser swaps, so, meh, more work and all, but whatever, life goes on.
EDIT: To add to this post, I'd also like to add that after adjusting the lasers pot and eliminating whine, if you are still getting skips past like the 72 min mark on a cd, then I would definitely try slight adjustments to pot VR101. That would be the last thing I would go to adjust focus though, not the first, personally. It also helps to speed things up on your final adjustments if you fast forward through the last 10 mins of the music cd you are using for testing a few times (you may want to alternate between FF'ing through the last 10 mins and also the first 10 mins to make sure its fine tuned on both ends of the spectrum). If still not focusing right, the laser will skip during the fast forward and you will get noise out of the speaker confirming this. You can also set the time counter to total time remaining to help spot the skips easier also just in case. Once you have eliminated these final skips and any laser whine you should be 100 percent set I would think.
