I have an early '50s 7U with steering lever play/slack. The tractor had a simple life in central California for 30 years as a pull tractor, picture #1. It made a lot more left turns than right due to life in front of off-set disks and plows. Picture #2 gives an indictation of its life today.  Play is in the lever shaft (bushings in the case cover) and in the pins and clevis' along the linkage to the clutch yoke and spring assist. The right side has much less slack and the clutch adjustment screw has over an inch of travel remaining.  It's the left side that needs rebuilding in the next year or so.  Adjustment is down to 1/2 inch, much due to slack in linkages.  All will be rebuilt when disassembled. The tractor is at the ranch 1100 mile from home.  Questions; 1) can the trans case cover be removed without removing the fenders? Removing hydraulic lines, seat tank, air cleaner, etc. is easy compared to removal of cage and fenders. 2) what is the part number for the steering shaft bushings?  I don't see the bushings displayed or listed in the D4 parts catalog. (grease zerks are shown no bushings)  I can fabricate bushing if required. 3) any tricks in refurbishing the linkage yokes? Drill to larger size and use a larger pin?  4) Are new yokes/linkages available?

Sorry to say but you're going to have to remove the canopy and the fenders, seat tank to get the transmission top cover off.
I've drilled out the worn linkages and fabricated new pins with good results.
I'm going from memory cause my 7u parts book is in the shop, but I don't think there are any bushings on those shafts. Seems like I've heard of guys making a bushing and boring out the case. Maybe someone more experience will chime in
Nice looking tractor

Check out Pacific Northwest Hillbilly video on YouTube. He has a very good video on this topic.