In the arena today.  Ground work first on the 22' line.  Worked on yo yo, which he actually did pretty well although we need more regularity in the steps, and circling.  In the circling he was also better at staying out on the line.  Then asked him to full pass over the 20L drum from either direction.  Again he was reluctant but he did do it. 
     Riding was a different story.  He was fine with all the things he knows so well (was he asleep?) but as soon as I asked him to full pass over the drum he became tense.  Walked through the bridle or moving into rather than away from my leg.  Worse when asked to step forward he went backward.  Hmmmm.  Decided I would make the wrong thing difficult and the right thing easy.  Decided to be quiet with my aids when he was standing alongside the drum and noisy when he was against my aids.  Noisy did not mean harsh or hard, just niggles with my legs, niggles with the reins (in my bitless crossover bridle).  Even so it upset him.  I thought he was getting the idea for when he did stand beside the drum I sat stone quiet on his back.  I'd wait for awhile, 30 seconds?  a minute?  then ask him to take one step over toward the drum (full pass).  Then it was on again, against my hand, against my leg, me niggling until he was in position and all would be quiet.  The third time Balthazar had had enough, before I knew it he'd launched himself stiff-legged into the air just as I've seen him do in the paddock when he's playing.  In a way I don't blame him.  Whatever he did (except for the correct thing) didn't shut up the 'noise'.  He couldn't go backward or forward or sideways (away from the drum), the only direction left was UP. 
     Dismounted and went through it all again from the ground.  Again he was successful on the ground.  Got back on and the same thing happened.  I didn't want him to learn that the way to escape something he didn't want to do was to go up (would the next thing be rearing?  Sure don't want that!) so when he went backward when asked to go forward I got him to go forward in big energetic trots around the arena interspersed with changes of direction and 20m circles.  Would return to the drum and ask again.  Again, if he went against my leg off we'd go, big BIG trots (didn't know he had it in him - are we finally tapping into that forward impulsion he's kept under wraps? I have known for a long time that even while he's apparently going forward quite happily he's sucked back.   Not allowing that energy out and having it available is really the source of the going UP rather than forward or sideways).  Anyway, we did that a few times until finally he realized that standing quietly next to the drum (or witches hat) and listening to my asking leg - and I wouldn't ask much, being happy with one step in the direction asked for) resulted in success.  He full passed over the witches hat.  Dismounted and made a big fuss of him.  Unfortunately he was grinding his teeth, something he hasn't done for a long time.  But do I give up just because it stressed him?  I don't think so.  I never punished him, was never harsh, just asked that he either listen to my leg or go forward.  The stress resulted in that he had to try, had to, in the end, do it.  I didn't give up, just quietly persisted. 
     Took him out for pick afterwards.