we have a similiar noise here in new zealand, google the 'devonport hum new zealand', everyone thought it was coming from the naval base or the old war tunnels in the hills behind but nothing has eva been confirmed.
We've got one of these, awesome machines, made in austria. You can get the manual online now, we havent got the planner on ours, hubbys gutted its missing.
we have a similiar noise here in new zealand, google the 'devonport hum new zealand', everyone thought it was coming from the naval base or the old war tunnels in the hills behind but nothing has eva been confirmed.