From what I remember, the fireboxes are too thick on the new boilers (201/316 and 500/1316). This caused extra flex and within a year and a half operating time the stay bolts worked themselves half way through the sheet. This was on the 316, and the 1316 firebox was made even thicker.
Earl did tell me the plan was to keep the boilers, and replace the fireboxes. Not sure how soon on the 316, maybe this year. The 1316 is probably going to have to wait till all three steamers are running reliably.
Casey