Couple things to look at here. First, I would check the tension in your steering chains. They should have just a little slack, as they can work somewhat against each other when too tight. Often that "sticky" feeling is the springs on the chain connectors stretching. Second, I would check to make sure the nut on the pivot bolt is not over-torqued. Rule of thumb is to tighten firmly on reassembly, then back off until fork moves without undue resistance. If neither of these troubleshooting options applies, you should inspect the internal components of the tailwheel for excessive wear/missing or shifted parts. Also, if you are running all 5 compression springs in your tailwheel, you can take 2 out and only run with 3. It's very common on lighter aircraft to run only 3 springs and doing so can give your tailwheel freer movement. I hope this helps, let me know if you have any other questions.