The Canon PowerShot A480 is a compact digital camera with a telescopic zoom lens; mine runs the CHDK firmware add-on. After about two years of use, I turned my A480 on one day, and it wound out its lens — then stopped and showed "Lens error, restart camera" on the display. Restarting didn't help — the lens was jammed solid.
The camera is reasonably easy to dismantle: remove the externally-visible screws, and work a soft plastic tool (e.g. a guitar pick) around the seam in the case to open. Note that the screws have different lengths; keep track of where each screw you remove came from. The LCD display is similarly held in place with a few screws.
Once you fold back the LCD, you can see the camera's PCB on the right, and the lens/CCD assembly on the left:
To take out the lens assembly, you need to disconnect the two ribbon cables from the PCB, and remove some more screws. It's not immediately obvious how to do this: each connector has a small brown cover that flips upwards, away from the cable, so you just need to lift this with your guitar pick. To reconnect the cable, push it gently into the connector and flip the cover back down.
Having removed the lens assembly, I tried to unjam the lens — tricky, since the plastic gears in the gearbox (which were obviously pretty worn) aren't held in by anything, and the ribbon cable — which I didn't want to desolder — wraps tightly around the case. I did eventually manage to free it up after a lot of fiddling, but refitting it and powering the camera back up just meant it wound out the lens and jammed again...
Instead, I bought a replacement lens assembly for a few pounds from DHcameras, which was straightforward enough to fit. To get the screws in around the lens assembly, a magnetic or sticky screwdriver was useful. The cover clips back into place — remember to fit the rubber connector cover first.
The repaired camera now works fine. I wonder if I'll have to do this again in another two years...