How could I find out where my ex works so I can go for child support?

My ex currently owes close to $3000 and hasn't done his taxes in years so I haven't even received his GST or tax returns. I am finding that Maintenance Enforcement doesn't seem to actually try to find him so I have to do it on my own but his friends won't tell me anything and I have asked ppl I know that I know if they know where he is working but no luck. I want the child support to put my son in Tae Kwon Do or something like that.