I know, what your getting at, mate ?,...but, to be honest, if a "modern duffus", is 'installed' correctly,...this shouldnt really happen ?
Yep shouldn't happen but it does. Maybe we have clever moles up here!
Well, on a rare occasion, i have had a trap, shifted ?,.i suppose ? (pushed up, a bit),..when theres a severe, overnight dip, in temperature,usually ?,...& moley decides too 'tunnel deeper', shifting alot of soil ? (im "up here", too ! lol,...not too far away)