Anyone been affected by the windfall elimination provision of Social Security?

Today I was informed by a friend that I will not receive full Social Security benefits if I did not put in a 30 years of substantial income. I put in 15 years of substantial income and about 6 years of part-time income before moving to Canada in 2006. Since 2006,I have probably put in one and a half years of substantial income since then being deployed. I do make about $12k a year from my drills with the USAR. Does anyone know the formula of how they prorate your Social Security benefits from what is posted on your yearly statement to what you actually get if you didn't do the 30 years required? Have any of you had this problem? One of my friends worked for a police department in California and he could not collect his full Social Security due to being paid by the public employees retirement system so he's only collecting about $200 from Social Security even though he did 5 years active duty(31 years total time in the RA and the USAR) in the army and he retired with about 4000 points total. He is receiving his regular army retirement.