A833 1-2 Clutch Sleeve Gear Binding

Those guts look pretty nice but;
that is waaaaaaaaaaaaaaaaaaaaaaaaaaaay overshifted into First. Yur not working on a motorcycle trans here, lol.
Put the synchros into neutral, and Remove the 3-4 fork. Level the cover surface of the trans, front to back; by eye is fine.
Put the 1-2 fork in neutral, and
then install the cover. Install the two special long-shouldered bolts into their respective locations, and snug the cover down with just those two bolts. Spin the output-shaft while shifting into first. After it snicks in, continue to rotate the shaft another turn. If your rear seal has a dustboot on it and it is difficult to reach the M/S, then just spin the input gear. It'll be Ok .
Stop, remove the two bolts, and very carefully lift the cover straight up, leaving the fork behind. Don't touch anything else!
After the cover is off, just look. See where the slider ends up, You might find an Eighth of an inch or more between the face of first gear and the face of the slider. This would be normal.

You see where the small pointy clutch teeth are on low gear?
and you see where the matching pointy teeth are inside the slider?
Well, the slider teeth only have to overlap the clutch teeth by about 6>7/32nds inch (That is about .200 inch give or take), to do their jobs; any more is overkill.
Here's something else you can do;
Stick something down between the clutch teeth and the low gear, like a paint-department stirstick. Snuggle it up to the face of low gear, allow NOT more than 3/32 between the opposite side of the stick to the back of the clutch teeth. If you have more, insert a shim next to the lowgear to push the stick in the direction of the slider. Now, push the slider over to the stir stick. That going to be about the correct amount of engagement.
Now see if the slider still wants to hit the cluster, lol.