Here is a recent service change we did in a local retirement community. The panel is approximately 40 years old, and with the cover on, looks fine to the untrained eye. There were no roof leaks above this panel, and it was located in the garage.
All equipment has a service life, and this one has past its usefulness years ago.
It appears condensation has played a part in damaging the breaker terminations over time. When you have temperature differences (outside vs inside the garage) condensation is bound to form. Here is the result of years of temperature variations.
The conduit between the inside and outside of the home should be sealed in order to limit this type of damage.
Before
After
