18913 grinding range shift low to high

Was having issue of grinding on the low to high range shift, and the splitter wouldn't stay on the low side if you were coasting down a hill. So, ordered most of the hard parts that I figured would be an issue with all of the grinding. This is a used transmission that I recently put in, but has had this issue from day 1. Has a Weller reman tag. Just finished getting the auxiliary back on. Didn't see much of anything wrong inside, but changed the reduction gear, sliding clutch, splitter yoke, synchronizer, and o rings in the splitter cylinder. Had already changed the air regulator and the splitter end cap. It now stays in low with the splitter, but still grinding on the low to high range shift. What else could I have missed?

 

Switch on shift tower is new as well. Was replaced recently before I switched to this transmission worked fine previously

 

Update on this transmission fiasco. Ran for 2 weeks. I only run about 800-1000 miles a week. Transmission started making some noise at the end of the last run. Output seal leaking. It was hot and low on oil. Put some oil in it to get it back to the shop. Pulled it and took it to my rebuild shop. Apparently the problem started with a broken output shaft bearing. This was letting everything walk, and took out the seal. Apparently also the cause of the bad shifts. Roasted 9 gears in the main box, along with the new synchronizer and shift fork. $3500 later and it's picked up and hopefully going in today.

This started out as a 10 speed to 13 speed swap over a year ago. Bought a used transmission. Had the wrong transmission shipped, took a year to get this one. Have close to $15k in swap, along with clutch, rear motor mounts, driveshaft rework, etc. Should have just bought a reman and paid the core. Would be about the same and about 30 hours or more less labor. At least I do most of my own work.

Thanks for all of the advice.