You only need to remove the front fascia, not the back. Then you take off the top zoom/dial fascia, under which you get to the zoom button/rocker. To take off the front fascia, apart from the screws on the sides, don’t forget two screws in the flash compartment. Pull off the front. Unplug small ribbon connector to the left of the flash (as you look at lens) near another screw. Unscrew this screw. Then the top zoom/dial fascia comes off with a bit of prying - don’t touch big battery capacitor tube with finger or metal, it may have a charge. Under the top plastic fascia/panel are various screws and plates, pretty easy to unscrew these to expose zoom button which must be pushed out from between two small spring levers - easy. Debris gathers with age around inner circular periphery of the plastic zoom rocker. Use a screwdriver to clear it out, and wipe away remains. It will then go back and forth smoothly when assembled back with the two spring levers, as it was when new, without need for lubricants. Reassemble.

Best video showing proper teardown:

https://www.youtube.com/watch?v=Gje1QFH0...