Hi Beernard
Definitely seems to be inside the light unit itself then.
If you feel you can manage it without hurting your thumb, then the glue around the light unit needs carefully "cutting" out with a sharp craft / utility knife as much as possible (nice thin blade).
Obviously, removal of the unit is required first and this is really easy. You should be just about able to squeeze it out once undoing the screws.
I also used a hair dryer to help heat up the plastic once I'd removed as much glue as I physically could - but I'm in chilly UK and this was in back in September. I didn't want to risk breaking cold brittle plastic. I'm sure your weather will allow you to skip this step
You can then prize open the light unit to get at the gubbins.
The way I see it, the unit is dead - you have nothing to lose (except a thumb
) in taking this unit apart. They are classed as replaceable, so any attempts to repair it are always worth it in my mind. My repair cost hardly anything, where as a 2nd hand unit for me on ebay was pretty pricey - a brand new one even pricier.
I would remove the light unit, and give it a shake, see if you can hear any lose components - I'd be surprised if you don't. The light units seem to shake themselves apart with vibration.
Let me know your thoughts and findings and good luck