I have a ML300RTW and I do not hear any noise from the unit or ticking from the timer. When I advanced the timer to check if it would send power to the lights, they come on and when advanced to turn off time they shut off. So, it still sending power, but thetimer does not work. Is there a repair item for this and who does one obtain one and how to install? Thank you, Ron Ragno

Power packs do not have repair parts anywhere on the internet that I know.
Occasionally folks take power pack apart, but nobody reports being able to repair transformer or timer.

Once power pack goes bad, then it needs to be replaced.

Good news for your specific problem however:
'Harry' wrote to fixya with some information.
His timer stopped working so he bought cheap plug-in timer, set power pack to override, and then plugged power pack into cheap timer. Cheap timer turns lights on-off.
Harry also said his power pack has 5 year warranty and he was negotiating with Malibulights.com. No word how that came out.

Best I found are tips for next power pack that might save money:
The reason I add tips now, before your power pack needs replacement is some fella wrote fixya.
He bought 500 Watt power pack to replace 300 Watt > thinking bigger was better.
Power pack burned out. Here's why:
a) Match wattage of bulbs with wattage of power pack
Lets say you have fifteen 20 watt bulbs = 300 watts, so install 300Watt power pack
b) Installing a 500W power pack on 300W of bulbs will burn out bulbs and power pack.
c) Replace bulbs as soon as they burn out or other bulbs will burn out and power pack will burn out.
d) When working on bulbs, unplug power pack or power pack may burn out.
http://www.malibulights.com/guides_support/low_voltage_planning_guide/select_your_power_pack

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.