I've got the Pullrite 18K and have the same challenges. You are doing it the same as me but I now I try to have the TV and 5er straight when I finish parking, then I set my chocks and raise the landing gear until the pin height is centered in the jaw. If it doesn't release I move the TV forward or back a bit as appropriate to relieve any stress and that usually works. It also helps to be mindful of any grade on your new site. If you had to push it uphill to park it then you will probably need to pull forward slightly after the landing gear is down, etc. It's all about finding that sweet spot. Once you find it life gets better.
Also keep up the good cleaning and lubing you have been doing. It does help.