FYI..Possibly battery clip is now loose because of being changed out so many times over the years. I know this is common practice.
Personally I read coin cell battery voltage at diode D4 (D4 kinda sounds like Dover) on CLC located very near CLC battery. Read voltage at the end of diode pointing towards battery, if under 3.0 volts then replace battery. Otherwise leave it be. These batteries last for years in my experience, and it easy to catch them with low voltage in plenty of time before you get a cold start.