cub steering box thrust washer?

my cub has some up and down play from the steering arm which attaches to the bottom of the box, i tightened the nut, got 1 castle and it was tight, but the play is still there, about 1/4 inch to 3/8ths up and down movement, i adjusted the toe in today too, as it measured about 1/2 inch of toe out, i got it to 1/8th inch toe in now, the reason for all this is after i got done mowing 15 acres the other day i put her in 3rd gear and took off,once i got it running in 3rd gear about 3/4 throttle, the front wheels went to flapping like a butterfly , now this cub never did this before,the manual showed a thrust washer on top of the steering arm, which im assuming is worn, and thats where the slack is coming from, but i have looked here and on stiener tractor parts and nobody is showing a thrust washer, so, does anybody know where to get one or just what its deminsions are? im assuming its brass, or any other ideas?

Eric, there are two brass bushing in there and seal on the bottom, the bottom bushing is the one that takes care of up and down slack and both for wobble in shaft. Go to IH and you can pull up parts picture and order right on line or go to Case IH dealer. Those two bushings will set you back $100. Stiener has the seals but Case I H has the bushings. Good luck I just redid a Cub this summer.

The thrust washer shown in the parts diagram is needed to keep the shaft from excess up and down motion. The motion should be controlled between the top of the lower bushing flange (internal), and that thrust washer. there is a pinch bolt on the steering arm that is responsible for arm tightness on the shaft. If the arm is removed, the thrust washer can be removed. In my opinion, the 3/8 movement would allow the steering shaft to turn and the worm wheel to spiral up and down on the worm gear from the steering wheel.
The thrust washer (if missing or worn out) could be replaced with a oilite brass washer fitted to the shaft, and of thickness to allow only .002 to .003 movement up and down.
If the shaft is able to move laterally more than .003, front to back, or the end of the steering arm up and down, the bushings - #14 and 18 in the diagram - are worn. The thrust washer appears to be outside of the box lubricant. This would be a place of high abrasive wear, and the need for occasional application of sprayon grease.
The spindles for the wheels also play a major role in wheel control. Jack up the front (one side at a time) and shake the spindles in and out to see if they have bushing wear. (greasing them when up allows grease to get in the thrust surfaces as well.
Mobile1 synthetic tube grease, or JD corn head grease, is my choice for gear box lube. They do not run out of the seals like 90 wt. Jim