For two people (one of whom has an arthritic ankle) to lift a heavy five foot square sheet of wood up higher than their heads and slot it into the grooves in a pair of cast concrete posts is tricky at the best of times. When you're squeezed between the fence and an overgrown bush, the wind is blowing hard against the panel, and the posts have moved closer together so it won't fit in the groove and one person has to let go with one hand to thump the post without the aid of a mallet? Hmm...
There's one more panel to replace and another that's on its last legs, but I suspect he'll have trouble buying any right now.