...but long term issues?
Then Kevin will have a life long customer. He tried to fix the system without just changing parts, which by the way, owners begin to notice after the second or third attempt. It does not take them too long before they begin to see what kind of tech is working on their system.

Once you loose your credibility with them, you could solve the problem the next day, and they will think you are guessing again.

Ripping out systems to "fix" problems is an easy way out. I hope the school you go to, does not condone this type of ethic?