I know this may sound dumb, but. All of the ovens I have been around that use the chain belt to move product, Have spring loaded idlers on the bottom of the chain to allow when product is added or to allow some flex for the chain. Why not do as some have done and add limits to idlers. When chain tightens up springs flex and limit makes. Regards, Tom To tweek it a little if you don't have spring idlers,add prox switches to slack area of chain and when slack is gone you know chain is getting to tight.