I'll be driving my jeep around an I'll come to a stop sign an I'll go to put it in 1st an it's like there's something blocking it, like a door I have to push thru. First an second I have to like slam them shifter into gear, third an fourth are easier but I still have to put a little force into it. But then other times it'll shift super smooth, any ideas what the problem is an what I can do?!,