On another thread Unit504 sent me a link for a 'how to' access the convertible roof hydraulic pump which was very useful. As a general question to roof experts, is there any way or need to bleed the hydraulic unit which operates the roof? For instance, I am assuming that if I replace any hydraulic ram I am going to get a loss of oil and some risk that air may get into the system. Similarly, if you get low on oil, air may get into the system. Any info much appreicated.