How do I reset my timing on my singer 2517c?

I removed the belt on the underside of my machine. I also removed the gear under the bobbin to regrease the shaft. Now when I put it all back together, it is out of time. Can you instruct me on the art of retiming my machine so that I do not have another expensive paperweight sitting around the house? The needle keeps hitting the bobbin and I have tried numerous times to get it right but I have been unsuccessful. Please send me an email at vanslykejeremy@yahoo.com. Thank you for your expertise.