This is not a common fault and not diagnosed by many but the solution is simple. https://electronicfix.com.au/mac-repairs-brisbane You are required to open the iMac to fix this problem, just take your time and be patient as rushing this job will cost you dearly. To see the fix go here https://www.youtube.com/watch?v=KcRoB3LrcUo We can perform this repair for any apple mac or iMac. Maybe you are looking for mac repairs near you, then you have found the right place.