the secret service took more than a year to replace a broken alarm system at the home of george h.w. bush , it has emerged .
the alarm failed at the former president 's houston residence in september 2013 and even though the secret service .
it took until december for it to be installed - leaving the couple without the protection of a working alarm at their home for 15 months .
it came despite an agent 's recommendation in 2010 that the alarm , which was installed in 1993 , be replaced because it had exceeded its life cycle ' .