There are several standard steps to take when narrowing down problems for a mod. Following these steps will aid an author greatly.
Sadly, some mods do conflict with one another. To determine which conflict, follow this procedure.
We'll call the new mod which has been added (and is having possibly conflict-related troubles) mod N.
- Disable all mods but mod N and the mods upon which it depends
This is the elimination step - if the mod is still broken, then you need to check the versions on the dependent mods - but it's not a conflict issue.
- Enable half your mods
- If the problem exists, disable half of the mods you just enabled and repeat.
- If the problem does not exist, disable the half you just enabled, and enable the half you've disabled. Repeat.
Each time you should be able to eliminate roughly half of your mods as being non-conflicting. You should eventually be left with just a few (perhaps even one!) that conflict.
We'll call these the C mods.
- Enable all of your mods except the C mods. See if the conflict exists.
If the conflict exists, then there are multiple conflicting mods. Write down the C mods you have found, and repeat this entire procedure - keeping the C mods disabled.
If the conflict does not exist, then congratulations! You have found the conflicting mod.
This sounds complicated, but is quite easy in practice. If you have 40 mods it should take 6 rounds to find the one you're looking for.