The obvious weakness is your quant score combined with somewhat weak math background. The coursera courses are good, and talking about them in your personal statement should help, but something verifiable is better. I.e. take calc at a community college this summer and get an A.
Also, you don't mention letters of recommendation. With some time out of school, have you kept up academic connections? You will need letters from active researchers to have a good chance at getting into a serious research school.