From what it sounds like, you should just use this sub from the FAF that I posted.  That way you don't have to content with a "goto" and you can use the #RESULT.  Just call it with:
gosub CheckItemDurability 5 #FALSE
 
Doing this, the sub itself won't warn you but it will return #TRUE stating that something on the paperdoll is less than 5% (or whatever percentage you want to put there).  Other scripts I put that value at 80% just to give me warning that it's time to repair.
oh, also keep in mind that the above sub uses a couple other subs that I think are the same from this script snippet for Durability, but here they are to be complete:
;-------------------------------------------------------
; %1 = #FINDID of item to evaluate
sub TM_CheckCurrentDurability
  namespace push
  namespace local CMD
  set !item %1
  event property !item
  set !property #PROPERTY
  set !search Durability , #SPC
  str count !property !search
  if #STRRES > 1
  {
    str pos !property !search #STRRES
    set #STRRES #STRRES - 1
    str del !property 1 #STRRES
    set !property #STRRES
  }
  str pos !property !search 1
  set #STRRES #STRRES + 10
  str del !property 1 #STRRES ; 87 / 87$
  set !temp #STRRES
  str pos #STRRES / 1
  set #STRRES #STRRES - 2
  str left !temp #STRRES
  set #RESULT #STRRES
  namespace pop
return #RESULT
;-------------------------------------------------------
; %1 = #FINDID of item to evaluate
sub TM_CheckMaxDurability
  namespace push
  namespace local CCD
  set !item %1
  event property !item
  set !property #PROPERTY
  set !search Durability , #SPC
  str count !property !search
  if #STRRES > 1
  {
    str pos !property !search #STRRES
    set #STRRES #STRRES - 1
    str del !property 1 #STRRES
    set !property #STRRES
  }
  str pos !property !search 1
  set #STRRES #STRRES + 10
  str del !property 1 #STRRES ; 87 / 87$
  set !temp #STRRES
  str pos #STRRES / 1
  str del !temp 1 #STRRES
  set !temp #STRRES
  str pos #STRRES $ 1
  set #STRRES #STRRES - 1
  str left !temp #STRRES
  set #RESULT #STRRES
  namespace pop
return #RESULT