Upon closer inspection both exhaust valves are broken in cylinder 3. The cams are out and I found this strange material on the timing gear. It is very hard and not metallic.
Looks like a sealant or repair material. It has been there for at least some revolutions. I found some small pieces of the same material in the oil pan.
I can't think of anything that is supposed to be in the engine that would look like this.
I don't see how this could have caused the broken valves. I would think that the chain tensioner would absorb the extra tension as the blob passed under the chain. It would be nice to know if the chain had jumped a tooth or two...