Question on hydraulics at BX 14

Hello and good day, since yesterday I am proud owner of a BX 14 TGE Classic, year ́91 with 160tkm. The car serves as a second car for Papa (me) to slide back and forth! At the car is so far as possible, it drives well, steers and brakes well. But now I have found one thing that I can not yet classify: The car sinks overnight, which is normal for the first time. However, it sinks only in the back, not in the front! When I yesterday evening the various “positions” of the Hydrauli k wanted to test it was so that the car was in the lowest position in front with one anchor but then in no other position in front always had the same altitude level. Heisst: In the back the hydraulics m.E. reacts normally, not in front? Also I had the feeling that I should not press the foot brake during the lowering/lifting of the car because it seems that I “block” the hydraulics with it!? Maybe someone knows advice, I would be very happy about your answers, MfG, 2016