I have a project that works perfectly in 476.4 but not in 487.
As I said before, one of the most helpful things you can do is test every beta release in between those release numbers, and identify the specific release number the problem first started in. That can narrow it down from hundreds of potential changes to maybe a dozen.
You can also speed things up by testing the half-way point - e.g. test r481, if it works then test half way between that and r487, if it doesn't then test half way between that and r476.4, etc. So you split the range in half each time.