Sounds like pump issue or loose wire and not the timer.
Check wiring at pump. Read pump manual. The pump may have overheat cycle
that trips off and then comes back on to protect pump without requiring
owner to press reset button each time.
If timer turns OFF, then the manual override lever moves to the off position, and when timer turns ON again, the override lever moves to the on position. If override lever is moving without a tripper, then I would like to know more about that. Add a comment with photo posted on Flickr.
Same with the circuit breaker. The circuit breaker switch does not trip and reset once a day.
A loose wire could cause occasional connect-reconnect.
Check terminals inside timer for signs of high heat and burning. Check that insulated part of wire is not under the screw-down-plate.
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-timer.html#plateCheck circuit breaker for signs of burning and smell of electrical burning and sound of shorting on the busbar.
Upvote the help.
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