2000 Sebring Convertible valve tick

My 2000 Chrysler Sebring Convertible with 46,000 is in near perfect condition. However, it has an intermittent valve “tick” at the first start of the day. It can take one to seven days or more to reproduce the problem. It sounds like a single valve. I’ve left it overnight with a mechanic but, of course, the noise doesn’t occur when needed. The engine has been decarbonized and I’m currently running with a Lucas Oil/Valvoline synthetic 10W 30 mixture both performed by a Valvoline oil change location I trust.

The engine is a Mitsubishi V-6 2.5 SOHC. Is there any way to find the valve assembly that is causing the noise? For instance, if I remove a valve cover, is there anything I can see or feel that will reveal the problem? Other than this noise, it runs like a Swiss watch. I would really appreciate any advice you care to give.

Thanks very much.