Have you removed the caps on the lift spool to check the condition of the parts under the caps.
The picture I posted above, is an example of a detent assembly. If you remove the cap, be careful as springs and steel balls may spring out. have a magnet close by or a rag over the cap when removing.
You may not have a float, but most loader valves do.
I also noticed a valve body bolt missing. Sometimes, loose bolts or over tighten bolts will cause a valve not to work correctly.