2002 Mini 5 speed. Sometimes when shifting up or down the shift lever will not go into any gear. I have found double clutching works as does holding the shifter in position with a little pressure on it and hitting the accelerator then it will pop right into gear. What is driving me nuts is that I cannot get it to replicate every time. The linkage is fine and the slave cylinder isn't leaking. The Cooper dealer suggested replacing all of the brake fluid or of course "Bring it on in." All help appreciated