Are you the original owner?
Has the company admitted to you the long standing defect or did you hear that from someone?
You could also write a letter to the company (addressed to the president or owner) and sent by certified signature that documents you intention to report this understood long term defect to the state attorney general and appropriate federal entities if the situation is not resolved by boiler replacement . This concern is especially critical if the boiler was certified to a ASTM spec for pressure retention (safety) purposes.
Its nothing personal, business. Who said that ? Oh yeah...
My experience is that a reweld will not do it, the metal is already infused with an inappropriate cocktail of metallurgical flaws that will propagate into a crack again.
Or this may be a good time to move on with a coal upgrade with the help of a lot of people here a lot smarter that me in the art of heating.