The CT21AM2(A) TV is a 51cm mono.
I got into the service mode using Menu 2357. Here's what I can adjust:
1. Cutoff Red 2. Cutoff Green 3. Cutoff Blue 4. Drive Red 5. Drive Green 6. Sub Contrast 7. Sub Sharpness 8. Sub Brightness 9. Sub Color 10. Sub Tint 11. Horizontal Phase 12. RF AGC 13. VCO Adjust 14. D Trap 15. Trap Fine Adjust 16. DL Time Adjust 17. DL Fine Adjust 18. Audio Attenuation 19. Limit Contrast (H) 20. Limit Contrast (L) 21. Limit Sharpness (H) 22. Limit Sharpness (L) 23. Limit Brightness (H) 24. Limit Brightness (L) 25. Limit Color (H) 26. Limit Color (L) 27. Hibright Contrast 28. Hibright Sharpness 29. Hibright Brightness 30. Hibright Color 31. Hibright Tint 32. Mild Contrast 33. Mild Sharpness 34. Mild Brightness 35. Mild Color 36. Mild Tint 37. Warm Red 38. Warm Blue 39. Cool Rred 40. Cool BlueThat's all I could find. I'm not sure if there are any other menus.
- Joe Cudmore (address now unknown)