Probably it never existed a 1081 official service manual from Commodore, it's look more like a NAPCEC service manual & diagrams compilation of the 1084 series and his variants, like the nap6523, 8cm505, 1084S, 1084P and obviously the 1081. It's more complete than other scans and the quality of the scans also are far superior. It has two circuit diagrams variants of the 1081, mono and stereo versions. It doesn't include a diagram for the Philips CM8500 or CM8501, they look like the 1081 but they are slightly different.
Text excerpt from page 25 (click to view)
TITLE: TROUBLESHOOTING
TROUBLE SHOOTING Circuit CD Symptom Cannot read the the table of contents. No display. No sound. Cause and Remedy 1.The inserted disc is upside down. Insert disc correctly. 2.Disc is dirty. Wipe it with a piece of soft colth. 3.Disc is seriously hed. Use a new disc. 4.Disc is seriously warped. Use a new disc. 5.A non -standard disc has been inserted. Use only a brand name disc . 6.Moisture has formed inside the CD desk. Wait about 20 to 30 minutes. 7.Defect in the servo control board. Replace or repair as required. 8.Defect in the CD pickup mechanism. Replace as required.