the typical drain is from the cowl thru that area to the bottom..both sides...the kick panel being out , I dont think would cause it to leak by itself, but the clogging of leaves will...prob. some leaves have deteriorated and make nice 'plugs' in the drain...just a good 'house cleaning' there should work..
you may look up "davey" ( not sure excactlywhich place he posted , but suspect this "tech help"...check some posting back..) w/ this similar problem , think he just got his fixed...
Bjorn