My son was driving around the field just fine.  Stopped to adjust the cultivator to bring it back home.  Went from lo 4th to high 4th to drive on the road.  It started to move and then just stopped.  

No grinding of gears.  It feels like it is going into gear on both hi/lo and individual gears.  A few weeks ago, I bought a new clutch cable and installed it but the clutch pressure feels good so I don't think it has to do with that.  We have driven it quite a bit since changing the clutch cable.  

I don't know if this is meaningful but I can put the hi/lo and park shift lever into each gear without pushing on the clutch with the motor running.  While in gear, I did rev the motor up to see if it would even creep forward or backward but it does not move.  It does shake a bit when I rev the engine which may be meaningful.  I did check the transmission fluid and it has fluid showing on the dipstick.  

I find it really odd that it just stopped all of a sudden.  Nothing prior to this indicated there was any kind of transmission problem or anything going bad.  I need some ideas on how to debug this further.  This is a power director 16 speed.  

My first idea is that it has to do with hi/lo.  I changed the hi/lo cable two years ago so it is a new cable.  Because it started to move and stopped when he changed from hi to lo, makes me think it is hi/lo problem.  Could it be stuck in between hi/lo?  

Any help is appreciated!

Power Steering is NOT working.  I turned tractor on and tried to turn the steering wheel right and left and it put up a lot of resistance and did not turn the front wheels.  

Does this imply that the hydraulic pump has failed?  That would be way better than the power director failing.  I can check the hydraulic fluid too.  I don't see a leak though.

I looked at the cables in the floor and they all work as expected and are attached.

Thanks for that labor fix info.  Since it is in front, you do not have to loosen the cab I take it?

What kind of surprises me is that this torque limiter just went bad without showing any signs beforehand.  I am used to having something kind of go bad slowly or at least start making some weird noises, or act differently.  it went from working great to not moving at all.

Agco is $175/hour but an Allis knowledgeable Indiana resource is more like $85-$100 an hour, I believe.

Looking at the Agco site, there is a spring, plate and disk assembly available.  Those 3 alone are about $1200.00 in total but not sure I need all of those parts.  Sounds like at a minimum, I need the disk assembly which is about $500.  I might as well have the crankshaft seal and PD seal replaced as you recommend.  Probably going to be about $3,000 is my guess.

Going to have to do it though.   Tractor runs too good to not repair it.  This is why we bought a 7020 tractor last year so we have a backup tractor that can pretty much do the same thing.