New Toro BBC belt squeels and burns

I have a 2010 Toro Recycler 7.0 Torque, 190cc, Model 20333, ser no. 310028308. I replaced a broken V-belt and cable brake BBC. The mower ran for 5 minutes then started squelling and the cable v-belt (self propel)started burning. I'm guessing it's the v-belt not the BBC belt. Is there some type of adjustment that I need to do? Does anyone know if the pully on top of the transmission can it be replaced and if this would help?

thanks