There are probably metal fingers holding a flange at the top of the plastic diffuser. Try pressing the plastic in at the top edge (where the plastic meets the black frame) halfway between the corners. Press gently so the plastic gives a little while pulling down gently. There may be just two fingers, so push the plastic on opposite sides and try the alternate opposite sides if it doesn't come loose the first time.
Harry wrote in news: snipped-for-privacy@googlegroups.com:
Don't pry, but PUSH through the notch while PULLING down on the lens.
There will be a small hooked tab in the lens above the notch. This hooked tab must be temporarily pushed out of the way of its receiving recess in the body while pulling down on the lens. There will be more than one of these, so once you've pushed/pulled on that notch, continue to apply downwards pressure on the lens as you push inside the OTHER notches, until the lens starts to come free.
This method of construction is extremely common in consumer electronics, and in other injection-molded products. It's annoying and fragile, but we're stuck with it because that's the way they do it these days.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.