GE 51587 has same instructions as Tork 601A single-outlet outdoor 24-hour mechanical timer.http://waterheatertimer.org/pdf/Tork-601A-Manual.pdf
Plug timer into outdoor outlet.
To set current time, rotate dial clockwise until current time lines up with arrowhead located on inner dial.
Dial is divided into light and dark sections that represent day or nighttime hours.
Reset time after power outage.
96 pins located around timer dial are used to set on-off times.
Each pin represents 15 minutes in 24 hour day
Move pins in-or-out with fingernail or pen to set timer on-off functions.
With GE timers, usually when pins are out, timer is ON.
When pins are in, timer is OFF.
Set multiple ON/OFFs each day.
Timer repeats every 24-hours.
Manual ON/TIMER switch located on inner dial.
Set override to timer for program to operate.
To override time and turn on Load, move override to ON position.