Which Heath-Zenith model is it? I have a feeling this is a question aboutÂ a motion activated light because those are the ones that usually cause an issue with manual override. Some older models may not have it. Heath-Zenith's site claims that all newer models do:
Post your switch model number, it always helps with a more concrete answer.Â Also, check out one of the old discussions about Heath-Zenith motion control switches here
Maybe you can use some of the suggestions posted in this thread.