1990 Buick Park Avenue piece of junk

I replaced the coil pack the computer module im about to replace the camshaft position sensor but I cant get the harmonic balancer off because there is one bolt 15/16 holding it on and I cant figure how get a hold back on it. my real problem was I bought the car we had to jump it it hadn't been started since January drove it approximately 50 miles. Drove like a dream got it to my buddys who helped me pick it up came out it wouldn't start I pulled a plug wire and tested a good plug n nothing its a 1990 buick park avenue