ticket 2014112510027379 says:

Searching for "Mozart Symphony 36" used to find the
article on that symphony, as similar searches by other works by number continue to do.
But it is now buried on the second page of the results, rather than being the
first result, and it follows results for quite a number of other Mozart
symphonies (with other numbers).

I verified it's now the 3rd result on 2nd results page (23rd result).

using &srbackend=LuceneSearch restores Symphony No. 36 (Mozart) to be the top result.

This was not a problem for my actually finding the article, as searching for
"Mozart Symphony Linz" still returns the link to that article, still entitled
"Symphony No. 36 (Mozart)," ironically. For symphonies without a nickname,
it would have been more of an issue.

searching for "Mozart Symphony intitle:36" shows the desired article as first result. All of the top 6 (as far as I looked) of the bad results mention this symphony by name (with number) in the article text (and some in the result snippets too).