Make sure you don't have loose wire on the circuit breaker or neutral busbar inside breaker box.
Move wires to another same-size breaker to eliminate breaker as suspect.
Make sure that only copper wire is inserted under terminal screw plate at timer, and no insulation is under screw plate. Check that stranded wire and solid wire are not on same terminal screw, and that wire gauges are same so you don't have #8 and #10 under same screw plate.
Some of the new generation box timers from Woods and GE run fast and slow.
The clock motor is not connected directly to voltage from breaker, but instead the power is routed through electronics so the installer can select different voltages. Some models automatically detect line voltage.http://waterheatertimer.org/Woods-timers-and-manuals.html
Intel was working on the speed problem for GE in 2010, but I don't know the result.
The speed-reliability problem is fairly common, and continues since I received another e-mail about the issue a few weeks ago, and I'm certainly not first on the list to receive reports.
Clock motors and all analog motors rotate a certain speed based on electrical winding and on electrical hertz or Hz. Hertz is the number of cycles per second that the electrical wave oscillates. Electricity is a wave, and Hertz is the wavelength. This wavelength is regulated at the power station, although there is a move to relax strict adherence to specific wavelengths to save money.
In the US, 60 Hz is standard, and you can see that number printed on electrical devices like your TV.
In Australian, 50 Hz is standard. For example, a 50 Hz motor would run different speed in the US.
I don't know if Hz is the speed-problem cause, or if Woods makes timers to meet the different Hz markets.
The fact that you got two timers with same problem makes me think there could be a mix-up in the product shipment, or simply a bad batch of timers. I've tested these timers and found them to be made much cheaper than predecessor time pieces like Intermatic GM40 electronic series.
I recommend Intermatic mechanical timers for pool pumps instead of the cheaper-made Woods and GE electronic timers. The clock motor is wired directly to power source, and replacement parts are available. Plus the mechanical timers are not as vulnerable to product failure and power surge.http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html