If I had a whining tensioner I would not even start it!!
It is just not worth the risk, as said if it decides to seize, it will first melt your belt against the pulley, then snap then bend your valves, possibly even crack your pistons.
Tensioners are easy to do, 10 minutes maximum, and not too expensive, about £35/£45, don't even need to take belt off to do one.
Just tension to correct tightness, tighten to 45NM(locknut) job done.
If you were anywhere near Narfork I would do it for you FOC.
tabetha