I had a harmonic damper come loose on our cummins this summer... 1800 miles from home. Not cool. Got it figured out though:
http://www.irv2.com/forums/f123/urge...ml#post4832158
I can attest to the fact that bad dampers can cause bearing wear... we had oil analysis over the last year (during which time I think the damper was probably working itself loose) which showed what had to have been main bearing wear... elevated aluminum and iron. It was a few PPM though, so after the repair of the damper, I did not bother to pull the pan and check the bearings. I'll do some more oil samples as we continue to run the engine over the coming years.
Your balancer fits over the crankshaft and is keyed... there is a lot of surface area there, so even if it was loose for a short period of time it's likely that there's no real damage? On our cummins, the damper (not a balancer since the 5.9 is internally balanced) relies on a small 3/4" post in the center of the crankshaft to keep it all concentric, and the face of the crankshaft holds it true front to back. In our case, the worry was damage to the face of the crankshaft, but we got lucky.
I did not have to change the front seal on ours... but a wobbling damper/balancer can definitely take out that seal.
If it were me, and if I thought there was a chance there could be damage to the damper or crankshaft, I would look up the spec for radial run out of your damper and give it a quick check with an indicator. Yes, blue loctite is in order here for keeping it from coming off again.
-cheers