I have a slight oil leak on the bottom end not really an issue but when I opened the screw cap to add a little oil I noticed a chunk out of what I figured out is my clutch basket. I have a whole spare motor (bad crankshaft and blown topend) should I just change my oil and change my clutch and basket out? Will the chunk of aluminium missing throw anything off balance? If I open the case what kind of sealant or gasket is best to use when I close it back up? Do I need to do anything else? What could have damaged the clutch basket so badly? Also when I go to kick it over there is a dead spot sometimes where the kick shafts just goes down without catching could the two be related?