A833 4 Speed Problems.

I thought that this would be the best place to get some expert advice. There are a lot of people that know 4 Speed trannys inside and out and I'm not one of them.
My car has been getting more and more difficut to shift into gear. It becomes even more difficult when the car warms up. That seems unusual to me because most things mechanical move/shift easier when warm. I thought it might be a clutch problem.
I removed the inspection cover under the bell housing and had someone depress the clutch and could see the clutch move away from the flywheel. So I assume that the clutch works fine. I recently had the tranny totally rebuilt and 4 brass synchros put it and within 2000 miles it started acting up getting worse as time went on. I don't dump the clutch or beat on it so there is no reason for it to be crapping out.
Now it is so bad that it is very difficult to get into first or even down shift into first when decelerating. The guy that rebuilt the tranny looked at it but said he thinks everything is fine but I don't agree.
He also said that I should be using auto trans fluid in it instead of gear oil. I've never heard of this?
Is it possible that the tolerances are too tight in the tranny so when everything warms up it tightens?
What could be wrong.
Also when I used to try to shift the car into reverse it has the inland shifter with reverse lock out I would have to turn the car off to get it into reverse than turn the car back on and back up. If I tried to put it into reverse it would grind. Could this be because the idle is set a little high about 1000rpm and there is centripital force moving the tranny even with the clutch depressed so it doesn't stop spinning and that is why it is grinding? Would lowering the idle to 700 make a difference or is there something wrong?

Any help would be greatly appreciated.
Thanks everyone.

Carl