Finally, does anyone have any good ideas to minimise dust entry to the machine other than putting the machine inside a cabinet.
Dust covers which are sold or shred a vacuum cleaner bag as
a DIY project.
I tried this, but airflow is very impacted. It's better to have naturally low airflow (low fan speed) than to put a barrier on the path (air will pass elsewhere, and will accumulate dust where you don't expect it : in the DVD-tray opening, near the connector palates, etc.)
Probably this is the case, but I meant if you have fan sucking air in, then put such cover beneath finger protector or between two finger protectors. But I was just a suggesting, probably someone have ruled it out, because fan might heat more by trying to suck a vacuum. Or vacuum cleaners have ~1kW motors because of reason.
I second you if you have just fans pushing air out. System will suck air from 'easiers' point available.
But dust is the most common material in universe.. :) You cannot get rid of it easily.