....the spacer/cushion of your watch is made from rubber.
I notice that my G5600e hydro watch is leaking from the back case and the glass.
It has been sitting in the drawer for few months, I never use the watch as the solar panel also cracked and oil is leaking.
I've opened the watch last night and I found out that cushion rubber spacer size is expanding about 3mm, so its imposible to reinstall the rubber.
I believe the rubber spacer expansion is enough to give pressure to the oil to seep thru the backcase and even the crystal, that is why the oil has leaked on my g5600 hydro
However, everything seems to be ok on my GW6900 hydro since the spacer is made from plastic
Some pics below for your ref.