There was a bad batch of feeder slats on the older Tr's. For your stone roll you can get rollers that bolt on the inside of the feederhouse that lifts the chain over the stone roll. This also quiets the feederhouse.
I think that they made the font drum smaller so that it could raise higher and allow more material to flow under it.Some of the chains were stretching and allowing the chain to jump a tooth on the top sprocket. The center chain sretched the easiest and then ran looser. I don't know about flights breaking.
