It will always eventually dry out but it stains the inside of the glass and in the end ruins the gauge face.

 

After 7 years mine finally fogged as well... I just took it apart... which can be done by very carefully raising the chrome around the back edge... cleaned it good... conditioned the rubber seals... put it back together and folded the chrome back over the back edge and sealed it with silicon. I have done this many times in the past with other speedo's... they all want to leak at some point in time. Fix rated low moderate skill... if you can't change the fluids on your own bike, don't try this...LOL