Partially reassemble the system and test it. If it is sufficient, leave it alone and finish reassembly.
To test the read percentage, get a few known good games and see which ones load. A minimum of 5 test games or more is recommended. Only adjust the laser again after each full test is done.
If you can get the game to load, play each game for a few minutes to check for stability, and note any issues. Tip: Some early systems are known to have minor FMV issues.