Question about LogiLink pressurized gas cleaner

depends on the type and amount of dust, but if that doesn't help, it must be so bad that dismantling is the only solution.
just disconnect everything from the power supply first, try not to hold the can upside down and avoid turning the fans, as this will also generate some current.
by far the best is to avoid dust from the beginning, e.g. with dust filters in front of the fans.
if you also make sure that more fans are blowing into the case than out, nothing should be sucked in through any slits.