The original score of the Second is fire damaged, but not completely lost: it is in the Sibelius Museum in Turku. Most of the damaged parts are at the tops and bottoms of pages (flutes, double basses), so the tuba part should be more or less complete. But there were some noticeable revisions after the first performance(s) - as detailed in the JSW edition. Having said that, I don't necessarily agree with the JSW edition's conclusion that the original score had twelve extra bars in the slow movement (first appearance of the 'Christus' theme). After examining the manuscript (the pages are badly out of order in Turku) with a view to continuity and handwriting, it looks rather as if he made two separate attempt at scoring the same passage.