PA-18 pilot reported a prop strike occurred when the brakes locked during landing roll.

Narrative

Solo flight in PA18 with wheel skis configured in a wheels down position. Locked brake during landing resulting in propeller contacting the ground. Landing surface snow covered gravel with areas of exposed gravel. Push rod connecting front seat brake pedal to master cylinder was discovered pinned under wheel/ski pump after stopping on the runway. Aircraft was stopped on the runway following the propeller contacting the ground. Front brake pedals were not used during the landing. No additional damage to the aircraft or property. Tower was notified of the aircraft being shutdown on the landing surface and a tow was requested. Aircraft was towed from the landing surface. Locked brake perception was insidious due to slippery surface initially and the drag increased rapidly just prior to prop contact. Mid roll out there were sounds similar to the back of the skis dragging if the pressure drops a little in the wheel ski pump or the skis are not installed properly but I did not process as possible brake lock during the landing. Sound was most likely gravel kicking up and hitting the ski from the locked brake. There was also a light quartering headwind with an approximate 5kt crosswind on the same side as the locked brake to add to the poor perception. The mechanical situation is preventable with adjustment of the ski pump installation to avoid interference with the brake push rod. I also intend to add a visual check of brake rods/cables to my before landing checklist and be more vigilant for unusual sensory perceptions that do not match my expected environment.