I'm now running with a JD-1070 that I got for running a NH-1012 Stack wagon (the hitch weight is huge). I'm also now running a JD-335 4x4 round baler that easily puts out 900# bales.Are you running with a YM1802 or an YM1820?
My machine is rated at 26Hp PTO and the balers I posted about work with this range, just like his Ford models.
I once tried the JD19T. The only downside with that series is the hard kick each cycle that shakes the back-end of the tractor. It's a common theme with the series. With filled rear tires, the kick/jolt isn't as badly felt in the seat.
The 'jolting' you mention is common when the plunger & stationary knives are very dull and their proximity is too wide. Also, a sloppy hitch connection allows the dead space in it to create a lag which increases the rocking motions. Keep the 2 machines tied together to take advantage of their total mass.
Another issue to face is the drawbar length position on the tractor. When hooked up, the CENTER of the baler's driveshaft on the hitch should be exactly over the drawbar pin. This ensures equal angles on the pto yoke and baler's U-joints. Height should be level, too. If not, you'll feel some vibration because the pto shaft is not delivering a constant velocity input to the baler. ignore this and you make tear up a clutch and chains on any machinery you run.
I noticed once that my hookup had developed an unusual rocking motion and found out later that the flywheel shear pin had broken and I didn't realize it at the time. This should give you and idea on how little effort the baling process is with the right tolerances and conditions.