Been there
I tried for 2 years to do a DIY fix by adding fluid only to have it continue to leak over time eventually causing the card bearing to wear requiring replacement. Don't waste your time is my advice. The likely problem is a cracked dome (virtually impossible to tell while full of fluid) or more likely, a crack in the rubber bladder. Neither are DIY projects. Best to check out the Ritchie compass service guy location and have them do it - still cheaper than a new one which is obviously the other alternative.Adding fluid only treats the symptom and doesn't fix anything.DonIllusion