massey ferguson 3070 pto no stopping

[robbb]

Hello from England I have problems on my massey 3070 getting pto brake to work .With a powerharrow on back it only stops when its dropped onto soil when I lift machine it starts working when pto not engaged . The autotronic was bypassed to drive the pto a couple of years ago .I have identified the solienoid that operates pto brake and run a positive to it surprisingly this still didnt seem to stop it , tractor is ok to use, its as you can imagine a bit dangerous not being able to stop pto, any advice gratefully recieved Rob.