Child Support

I live in California and I have a 14 year old son by my ex husband. My ex has basically dropped out of site and has barley paid me any child support. I recieved nothing from him in the past 6 years at all and he has not tried to contact his son in any way. When we divorced he signed an agreement to pay $550.00 per month in child support and although he did pay that amount for a few months, he mostly quit paying. He then started again but at only $100.00 per month. The checked were written by his wife not him and only came for maybe a year at most and then he just quit. The agreement was notarized and was filed with the divorce papers and signed (stamped by the judge). Is there a way to get him to pay at the amount he originally agreed? I assume that he is working but I have no idea where he even is. Last I heard he was in Bakersfield CA. I live in San Mateo County in CA. Would I have to pay a Lawyer to do this? I know I can fill out papers with the district attorney's office but I'm not sure I want to go that route. What can I do?

[vrzirn]

A private detective will find him for you; the D.A. will help you get the money.
He is not going to pay of his own volition so you either force him or do without.