Waiting to fix one Downside is that looking at them, I
can't imagine how I'd getting one apart without destroying
it. Is there a trick I can't see?

....

Some are easy to open, some aren't. Most of the ones I have will pop apart
with a scredriver at the seam between the upper and lower section of the
ballast housing.

Haven't had one yet that can't be opened with a screwdriver like James
says; of course, you do need to pick the right screwdriver ;-)

Cheers

Matthew Smith
South Australia