I just rebuilt a 66 SBC 283 and I have an oil leak coming from the timing cover seal. I noticed that the harmonic balancer was grooved when I assembled the motor but I didn't think much about it at the time. Anyone have any ideas on a fix without replacing the balancer? Wasn't there a sleeve available at one time to cure this problem? Is there enough room to add another seal(2 of them) to change the seal location? Thanks.