Refurbishing a Buderus coal boiler

I have a 1979 Buderus coal boiler that I bought used in 1980 and have used every winter since. I recently discovered I have a small leak as it drips several drops of water every minute. My thinking is it probably has cracked somewhere from the many years of use and heat. I'm pretty sure the material inside is cast iron. Does anyone know of a company or person that repairs Buderus boilers? Although I'm not sure of the model # I have to believe it is a pretty basic one as there is no stoker and I have to poke the fire by hand to clean the grates off. As I'm 62 years old I don't really want to invest in a brand new coal boiler as I would rather try and fix the old girl. I would appreciate any info anyone could give me..

Thanks.. Jay

You might try water glass (sodium silicate) its used to seal concrete and to preserve eggs. It held a crack in my dads ideal no. 7 steam boiler for 15 years.

Does the boiler have a tankless coil? That is a common source of leaks. Take the jacket & insulation off and try to pinpoint the leak, it could be a simple fix.

Being I have little to loose I'll take the covers and insulation off this weekend and see what I can find. I have to believe it's a very small crack as when I heat the boiler up it seems to stop leaking but I was worried it might be rusting out but I guess that's not a common problem. Thanks for the advice..
Jay