So I scrapped off the flaky old paint and painted it a soft apple green. I solved the broken vertical problem by simply cutting off the matching vertical on the other side to make it symmetrical.
Then I nailed it up along my front walk and twined a few branches of the Jackmanii clematis through it. I just love the apple green color I used. It's so much more fun than plain white! The clematis is very happy to finally have a real trellis to climb and I can hardly wait for the buds to open into huge showy purple blossoms.