Lasermad.com

I have what seems to be a repeatable problem with my clock. I set it up by:

1. button on battery unit away to the non-battery position;
2. pull out the power;
3. wait a minute;
4. power in;
5. battery switch to battery;
6. wait a minute;
7. do the position-the-nixies-carefully-until-it-flies dance;
8. toggle setting 3 (auto nixie off), 4 (24 hr) & when appropriate 5 (DST).

After doing this it's fine ... for a day or so. After that everything still flies, but the nixies won't turn on any more. Going through the above will make it work again for a few days.

Is there any possible cause for this? Where does the motion sensor live (it may be it's not 'seeing' me properly)?

Thanks