Glad you sorted it! Is your 156 a facelifted one? I took the cowling off mine and couldn't see any relay, but then at the time I didn't know what colour I should be looking for. They may differ year to year..........Also I've heard you may need to remove the steering wheel to replace the relay. Looks like in your case the access was awkward. Could you have removed it if you needed to?
Might try it again at some point. I remember once I gave the steering column a whack and the indicators seemed to work for a bit after that. So in my case it is likely to be something around there .