The timer module is not sold separately.
Some people report taking apart the module and cleaning gears.
Others report the gears are stripped.
Probably easiest to buy cheap plug-in timer, set power pack to override, and plug power pack into cheap timer.
These timers have a warranty with sales receipt showing date of purchase.
Open following link for resources and tips:
http://waterheatertimer.org/Malibu-power-pack-stopped-working.htmlTake a minute and vote on answer.