Hi jfe,
The DC1400 uses only marine grade stainless steel hardware, so it’s unlikely that any of the shutter button assembly is rusting. What you see is most likely rust staining caused by some contaminants or improper cleaning/drying after using in saltwater. I would recommend have your local authorized service center clean and re-lube the shutter button assembly.
Here is some important information regarding sticky shutter button, which is available on our website troubleshooting section:
www.sealife-cameras.com/dc1400-troubleshooting-and-technical-updates
1) "Exercise" the shutter button after it's been in storage by pushing it up/down until the button operates smoothly and quickly returns to its upright position. Also, push up on the shutter from the inside of the housing to exercise the button’s full range. If the shutter button is sticky and does not return to its uppermost position, the Focus, Flash and Menu buttons will not function.
2) Thoroughly rinse housing in fresh water after each use. Periodically soak the sealed housing in warm fresh water for about 20 minutes. Push all the buttons about 20 times to flush out any debris trapped. Allow housing to completely dry before storage.
Important: If the above information does not resolve the issue, please contact your local authorized SeaLife dealer or the distributor/service center in your country for repair service. SeaLife recently developed a Zoom Lever / Shutter Button O-ring Repair Kit for DC1400 (Item # SL7201), which may only be installed by an authorized SeaLife Service Center.
We hope this information helps.
SeaLife Team