What affects CBM installation/removal?

I have a character with all stats as 9 and 4-5 in mechanics, first aid, and electronics. Most CBMs (at least that I have had and have now) have, like, 70% complication chance, and uninstallation of Visual Distortion has failure chance seemingly randomly shifting between 77% and 89%, and after doing it about 10 times I couldn't uninstall it. Do I just need to get higher skills or is there something else affecting the numbers? Also with the autodoc UI having that warning, does having allies affect the chances?