I just got my tower .75 a few weeks ago, mine was stuck at TDC or close to it, heated it up with a heat gun to get it back down and removed the head and back plate, found one tiny pc of aluminum shaving inside, now just waiting for a nice day to get'r fired up, i will definatly preheat with the heat gun before attempting to start it. And based on my other engines, the tighter the better.