Al-Ko Sensor brake

[New Signing]

Ok men and ladies, i recently purchased my new boat and it is fitted with an AL-KO sensor brake. I've had my Pajero rewired to sort out the compressor not getting the power it needed and the compressor on the sensor brake now works. This is a brake away system so in theory should the trailer come adrfit from the vehicle the brakes lock on. When i jack the trailer up and disconnect the fitting from the vehicle i can feel the brakes dragging however not with enough pressure to lock the wheels. 

The other issue is that the electric brakes themselves do not appear to be working when i press the brakes. It has just spent a day down at my local mick and joes who couldn't work it out other than to say it might need bleeding and they dont have the tool to do it. Their other idea is that perhaps the master cylinder is ceased but i have my doubts about that as per the above.

Any of you gentle folks faced the same or similar issue?