Power Director??

   call your  old dealer  has  to be an old dealer ship serviceman   no proplem for them   they have   done 3 for us  still working good

Bob-  My Series 1 did this on the high-range.  I asked Bill Deppe about it, and he showed me a spot in a power-director clutch pack that had worn... apparently the detent area... and once it wears a bit, it tends to cause 'em to pop out.  He didn't mention any adjustment point... it is apparently an over-center detent concept.  Unfortunately, you have to split the tractor to get it out, then weld up and machine the parts, and worse yet, even though the unit kicks out, there's no other problems, and will continue working indefinately, provided you tolerate or overcome the lever popping out.

Now, the poor-man's fix, is to take the little sector piece down by the shaft pivot, and mill or grind a little detent IN it... at which point, the director will stay in place by virtue of the new detent.  My PD jumped out of high, which I initially solved by placing a foot on the lever, and shortly thereafter installed said detent.  It's worked fine ever since.  Someday, when I find that it's time to split and rebuild the PD, I'll probably weld that detent notch out and put it back to original state... or not...

But I'm no expert here... I raked and baled with my grandpa's Series 4 for many years, and never knew much about it... but got this Series 1 last fall, so my actual work-on experience here has just been the last year or so.

There are three different sets of shim stacks in the power director clutch. The the three sets of shim stacks are equally spaced around the power director clutch, and each  shim stack is broken into three groups of shims. In each stack there are shim grouped at the center and to the front and back of center. These shim stacks are to be adjusted so that there is a specified amount of equal spacing between the preload plate and pressure plate in the engaged and disengaged positions. The service manual goes into detail on the adjustment which does not require splitting the tractor.

Thanks for the tip, Rogers-  is that adjustment made by adding shims?  I take it they're accessible through an access cover?