Hello, the baffles will normally last a little longer than 4 years, the hotter you run the stove (more wood you put in at a time) the shorter the life of the baffle.
The baffle is made of cast iron... and it expands and contracts dramatically as the stove is used and then shut down, it is not a good candidate for repair at all.
There is welding rod however that can be used on cast iron, but in these high thermal stress applications I can't recommend it... the welding charge would likely be in the $100 range... with a fairly short shelf life so to spea.
There is a chance however that a real good welder with a lot of cast iron experience could weld it using a tempering technique, and produce a baffle that might outlast a replacement. That is a very expensive process however. In the $200 to $400 range, not such a good option in this situation.
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