i think the instruction books say till change in tone, then some others and videos say till it changes tone and one more
i do as you do, till change in tone and i get excellent results, i use heritage hg main driver
<iframe src="" width="400" height="225" frameborder="0"></iframe>Dust Ball from Dave Hakkens on Vimeo.
link has the story
OK this is way cooler than the *other* ball vac
http://gizmodo.com/5712525/
gentlemen
we can speculate all day BUT, until someone has one in their hands we will not know anything about the new kirby. . .
except for the given fact, that it will be better than a dyson