+1 on this. You DEFINITELY want to put the original driver back in there, if at ALL possible. These are very elegantly designed, high-performance speaker systems... IMHO, one of the top five things that Greg Timbers has designed while at JBL.
BTW: The same woofer is used in the 240Ti and 250Ti. So, that can broaden your search criteria a lot.
BTW^2: In worst-case conditions (i.e, you never find a LE14H-1), the LE14H-3 (as used in the Citation 7.4 subwoofer) can work as an acceptable replacement, according to comments I've seen by those who have directly compared the 'H1 and 'H3. The only serious difference is the use of a rubber surround on the 'H3, as opposed to foam surround on the 'H1. IIRC, the LE14H-3 is actually still an available part from JBL parts. You would DEFINITELY want to replace BOTH woofers in the pair, to make sure that the cabinets sound the same, if you did this...
Regards,
Gordon.