Sparton horn questions

[smittykid]

I figured I would ask the experts before I get into this project. I'm getting power to the horn. When I push the horn button on the steering wheel, I can hear the motor turning inside the horn. On a rare occasion the horn will attempt to "aooga" but it's pretty faint. I've tried the adjustment screw, but that doesn't seem to help. What should I be looking for when I remove the back cover of the horn? Mike's "A" Fordable parts sells a rebuild kit. Thanks