Yamaha FZR 600 3U grinding/scratching at load

Hello dear motor-talk friends… My first post here in the forum after the search function and all the other posts didn’t help me… I need your advice: At the moment I am proud owner and driver of a Yamaha FZR 600 3HE 91 PS BJ 1991. However, it has been causing me grief for a few days: every time I give gas comes from the bottom left, I guess in the height of the alternator a knaksen. I have therefore removed the alternator cover and pulled the rotor from the crankshaft and found that oil is to be released from the bearing which should keep the light mesh space “dry”. Speak the bearing that holds the crankshaft. But someone must have already botched it before because it was smeared over black “??Silicone??” for sealing. My questions now: Can it be that the bearing is broken? I always thought the bearing was a make grinding continuous noise when they go hops. But since the noise is a snap and only occurs at 2-4 thousand revolutions with load / gas, I thought it could be just as well somewhere else. Is such a case known to you? What do I have to do to fix it? Which parts do I need? Hopefully you can help me… I don’t know any more advice…