On October 30, 2000, about 1030 eastern standard time, an Eberle Pitts Special S1S, N39124, registered to an individual, went off the runway when control was lost during landing at Sebring Regional Airport, Sebring, Florida, while on a Title 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the private-rated pilot was not injured. The flight originated from Sebring, Florida, the same day, about 1010. The pilot stated that he made a normal landing approach and a three-point touch down. Immediately, the tailwheel began "hammering" or shimmying, and the airplane began tracking down the runway to the right about 10 degrees. The airplane then began to turn to the right as he locked the left brake. The airplane then ground looped to the right. He stated that examination of the tailwheel assembly after the accident showed the bearings in the assembly were worn out from dirt getting into the bearings, and the assembly was free to move sideways about 1/2 inch. He stated that this caused the shimmy during landing and that he normally operated from a dirt strip.