I have a MT765 (A model) that keeps getting air in the brakes.  The problem has been around for a long time, but it seems to be getting progressively worse.  The only 2 places I can think of for the air to becoming from would be the master cylinder and the brake cylinders themselves.  The brakes are internal to the transmission.  The master cylinder is not leaking.  I was going to put a kit in the master cylinder as the first fix, but the parts book shows the master to be "non-serviceable".  Looks like I will have to replace the entire cylinder.  I don't want to just start throwing parts at it.  Has anyone else had air problems?  If so, what was the fix?

I have lost my dealer in this area, so I am on my own on this one.