The reversal bath and color developer go first.
The reversal bath gives no inidation of anything bad.
The color developer however will have one part turn black or very dark brown if it is bad or going bad.
The first developer is 3rd on this list. It goes bad as it begins to form crystals. There is no way to test if it is bad except for dissolving it in the right amount of water and then running the process.
That is about the extent I can help you.