MF 165 PTO Shifting Problem

Need some advice. On my MF 165, with the PTO lever in the rear position the pump turns and I have full power on the front forks. With the lever in the forward position, the shaft and pump continue to turn (does not disengage) but I only have limited, weak power to the front forks. Any idea why the pto does not disengage when lever is forward?

Neutral position is with the lever in the middle of its travel range.

IPTO or Driven by letting clutch out half way?

I forgot to mention it has an independent PTO.

It sounds like you have an internal leak in the system or a stuck open relief valve. We have had problems with both. Sometimes a steel pipe from the pump to the ipto pack can split or crack at the union due to the dowels that hold the main pump becoming either worn or broken, thus letting the pump move enough to cause stress on the pipework. The supply from the pump goes to the sppol valve/diverter valve on the ipto pack. It either sends pressure to the clutch pack to engage the PTO or it diverts it to the brake to lock the PTO. It then goes to your remote outlet and finally through the oil cooler and returns through the front input bearing of the gearbox. I repaired a tractor that was showing similar symptoms to yours.... It had a stuck open valve in the front bearing thus letting the oil flow easily all around the system and simply dump back into the box. Another was loosing multi-power high range when the IPTO was engaged I found a inline valve on the lines up to the cooler with no ball and spring inside! Replaced the ball and spring from another tractor as a trial and it was perfect. Lever forwards should be PTO drive engaged? and you have no loader power? could it be a leak in the PTO pack?
I can only give you pointers, as I am a few thousand miles away, but good luck and if I was you I would think about using a combined flow kit on that tractor for the remotes...once you work with that you will never go back! The increase in loader cycle speed and the extra power is unbelievable.
Sam