The Inter mast do not fit the ball very well (round ball and round but flat mast base). Get a new ball and dip it in mold release. clean the mast base and mix up some marine tex or something similar put some marine Tex in the mast base and push the ball into the base tape and let dry. Pop the ball out and trim the excess Marine Tex with a Dremal tool. Now you have a perfect fit that won't wear. I did this on my I 20 and sailed it for 1000 miles and don't have any wear.