Tilt/trim problem

[cheeseyrider]

Anyone have any experience rebuiding the tilt/trim hydraulic cylinders? My resevoir keeps turning a milky color, drained it and re-filled ,same thing. Looked at the cylinders and you can see traces of oil around the end. Are they a pain to work on as opposed to buying after marked and replacing new? I know they make re-build kits and after market new. Any help pointing me in the right direction would be appreciated.