I agree with both above, I would not open the TS except when actually needing to change the batteries, then I would remove the o-ring, wash it in warm water and liquid Ajax dish detergent to remove all of the old silicone (and sand sticking to it). then with a q-tip or something similar I would clean out the recessed groove in the housing that holds the o-ring, re-apply a thin coat of new grease (silicone regulator grease available from dive shops) and seal the machine back up. I NEVER had a single drop enter my housing. Also dropping one of those silica gel packets in the control housing is never a bad idea. Oh, and no, there isn't a rubber gasket or seal at the coil connector, no special attention is needed other than rinsing it out with fresh water when you are done for the day, I have heard some put silicone grease on the pins, I never did, and never had a problem. You will find the batteries last a surprisingly long time with that unit. It never hurts to order a spare o-ring or two, I did, but never needed them. HH Joe