hello everyone, i fired up my sled took it for a test drive and after a few minutes and noticed a fast pitched knocking sound, then went down a cyl. pulled plug and found electrode smashed up. suspect piston hit it? rod bearing go bad? somebody has been in this spot i hope. we looking at a total rebuild ? i wonder how much i should expect to spend? and is it worth it . some thoughts if you have time , thanks all . happy sledin.