This timer appears to be Leviton LTB60
http://waterheatertimer.org/Countdown-timer-horsepower-ratings.htmlTimer has 1 year limited warranty, evidently from manufacturer.
If timer is making humming sound, then it is defective, possibly receiving undervoltage on the line, or wiring installed incorrectly.
Switch noisy timer with one of the other timers, and see if problem follows the timer, or is related to the specific location.
Otherwise replace with LTB60 from Amazon for $24.
Or buy Intermatic Ei200 timer, or replace non-electronic with spring-wound timer such as 60-minute Intermatic FD60, or 30-minute FD30, etc.
If you need further help, I’m available over the phone at
https://www.6ya.com/expert/gene_9f0ef4df2f9897e7
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