Originally Posted by
speakerdave
It may be that the "modification" has already been done. That is to say, if the original 2440 diaphragm has been replaced with either the aluminum or titanium diamond surround diaphragm, that crossover will not work. There is no low pass filtering on the high end of the pass band for the horn, since the 2440 diaphragm crashes at about 9k all by itself. I would check that first. If the 2441 was used instead of the 2440--it is much more common--that is likely the problem.
If the original diaphragms are still there, there may be some aging effects in crossover capacitors.