I have found that when the coil goes bad (some times the sign is that the resistance of each coil pack is no longer between 11-13000 ohms-this is probably 80% true as an indicator), it puts a strain on the module so that it may fail sometime after. Therefore, it's a good idea to go ahead and be prepared to change it as well.
Gooey potting compound as yours was, tells you that the module has been overheating and is well on its way to failure.
When the module fails, it does not always mean the coil is fixing to but it won't hurt to change it if you want to. If the coil was still in range, put it on the shelf because some of the new stuff may not last nearly as long as the original.
If the coil fails, it puts a lot of strain on the module and that means it probably should be replaced as a preventative measure. Again, if it was running okay when you discovered it, I would put it on the shelf as back up just in case as I said about the coil
