water leaking from the boiler

Any number of reasons. I'm not familiar with how the Pencco is put together, but if it is sectional it could be the seals between the sections. Could also be a plain vanilla rusted out place. Could also be a plug or fitting on the boiler leaking.

Whatever it is you need to find it. Sometimes a leak is repairable. Sometimes it isn't. Whatever, I've yet to see a leak get smaller over time...