After using many different types of tailwheels this has been the simplest and best setup for me. Make a tailwheel out of piano wire to suit your setup and size of plane. Install a brass tube in the tailpost with an I.D. same as O.D. of the piano wire. Make sure to reenforce the tail post area with a block of hard balsa if it isnt already. Use a wheel collar that has the set screw replaced with a 4-40 x 1-1 1/2 socket head screw. Use a stiff spring
(I found all different sizes and stiffness at ACE Hardware) wrapped around the piano wire at the collar and attached to a small eyelet screwed into a hardwood dowell in the rudder. The collar is easily tightened with a ball socket thru the end of the spring. The wheel setup will not fall out of the brass sleeve because of the pressure provided by the spring. Easy to repair and replace parts. No more lost wheels if you solder a washer on the end of the wire to retain the wheel.