Leading employees older or more experienced than you
If your most senior tech has been in the trade longer than you've been alive, the leadership has to fit that.
Lead with respect for what they know
Ask their opinion before announcing changes. Veterans don't need to be managed. They need to be consulted, then aligned.
Hold the standard either way
Experience doesn't earn an exception to behavior or quality standards. Respect goes both ways. Senior people who slip get the same conversation as anyone else, just delivered with more nuance.
Use them to teach
Veterans who become mentors gain renewed engagement. The shop gets a training multiplier for free. Win-win.
Take your version of this question further
This is one operator-tested angle on the question. Your shop, your size, your trade, and your team change the answer. Ask your specific version inside Ask a Shop Owner to get a response grounded in how owners like you actually handled it.