Replaced Starter Makes Noise, Engine Turns Over But Won't Start.

I just replaced the starter in my 92 Ford Escort LX-E (1.8L), and although the engine turns over, it doesn't start. The starter makes a clacking noise, like it's still engaged to the flywheel as the engine comes to rest after a failed start. The old starter was an aftermarket, and it appeared someone had ground down the metal lip below the bell housing to perhaps better seat the old unit. I'm wondering if I need to add some shims, or if maybe the battery is weak (the power windows are slow to roll down currently) and the starter isn't getting enough power to crank the engine and/or properly engage the solenoid. This is my first starter change, and would like to know how to properly shim the starter, or where I could find a service manual that would detail the process. I'll try jump-starting it tomorrow, but have a feeling the starter needs some adjustment. Any advice is appreciated, thanks!- Nate