Nasty Idle Noise

Well, I've had my '84 944 for a little while, though it hasn't seen much time on the road because I've had a lot to repair on it since I got it (the tach, odometer, and fuel gauge STILL don't work), but I was just finally getting comfortable with it when it threw me for another loop today. I was driving the car, made a pitstop, and when I went to start it again it made a rather odd noise that sounded kind of like fuel pre-detonation, then spun back down. I turned the key again and it started up, but now at idle and slow coasting speed, it rattles like there are nuts and bolts kicking around in the bellhousing. At mid and high rpms, the noise vanishes, but I think there's a slight vibration and change in the engine harmonic that wasn't there before.

Even though I haven't put the car through any real paces or driven it hard, I'm thinking the starter might have somehow cracked the flywheel. Any thoughts?