About a year ago I had an annoying click coming from the pedal/centre motor area of my bike, once per revolution of the pedals. I eventually found that the click seemed to be caused by a broken reflector strip on the right pedal and the noise disappeared when I replaced the reflector. About a month ago a very similar click became noticeable but the reflector strips were intact. I have now identified the source of the click and it's my right knee! I don't know whether to be happy that the bike's OK or sad that my knee isn't. The click has been cured by wearing a support. Thought this might be of interest to anyone with an undiagnosed noise.
Jim
Jim