rear PTO lever wont engage sometimes

[coolhl7]

My rear PTO lever often wont engage on my MF1540HST. sometimes it will. sometimes it wont. however, if I turn the yellow PTO knob on the dash for just a few seconds I can then engage my rear PTO. The manual says to never turn that yellow knob w/o first engaging the rear PTO but what else can I do? otherwise the MF1540 has been flawless.Thanks

 

[Taiser]

Not sure of the MF's but does it do this even after moving the tractor a bit? This happens sometimes on my B7800. It's just the gears not meshing. If I push the clutch back out and in the lever then slides right in or failing that, just touching the hydro predal will work too.