Problem with the brakes!!

Hi fellows,

I got a problem with the brakes, first of all , I have a lot of years behind de Joke, about 30! I fly mainly big airplanes, I notice that when I go taxiing to the rwy the left brake, go in diferencial brake mode,just like that, I don't do nothing, the plane think for himself, I notice this, because when hay give fullthrotlle the speed doesen't go up normally, and I reach the end of the rwy, with no speed for a safe rotation!!

Same happend when I'm wainting for the permission for "Pushback" sudenly the brakes are off(not because me, but just like that, no reasson at all!!

I know that I have to change something in the Settings/Calibration!! but is so very long time ago that I was working in this part of the simulator, that I don't remember any more what it was!!!

I'm a old (70 years)guy but I stil have a lot of flying time in me! I hope so!!

If someone can help, Ill be very thankfull!!!!

Thanks for your time!!!

Cub51