have none of the techs who visited ever done a check off the cabinet,if they get the same fault as in the house they can refer it to a network tech,these guys have a better escalation path than the service techs.i.e. they can ask the people at surveillance to keep an eye on your area,every time the rtn path drops they can see it on the area rather than just your equipment,may be worth a shot to get a tech to call and suggest he passes it on,dont know,may help.