RCA 8T-241 fine tuning

[pearsonk]

Thanks all, bandersen's pic is exactly it............ its 1/4" wide and hard as a
rock. The tensioner makes use of a all rubber belt not practical. Original was
layered fabric, not sure if it was rubberised or not - construction probably similiar to auto v-belt, but flat.
I hoped someone had solved this problem already, I'm still trying to figure out
an off-shelf solution.
thanks again............