I have had to replace the hinges of the horizontal tail of my Zenair Zenith and in the process had to loosen up the control cables and now cannot remember the process to  tighten the cables to the correct tension of  40 +- 5 lbs.
   I thightened the cables with the turnbuckles until they are thight and there is no play between the horizontal  tail  and the control column but how can I measure the correct tension of about 40 lbs?
   Please advise
   Yvon