How can I tell if my OEM dual mass flywheel is bad?
 

What generally happens when these go bad? I have the flywheel out of the car and it seems to have some play in it- is that normal?

Thanks for helping the noob!

I believe I've found the answer
 

From service manual...
Attachment 434298

The "movement amount of radial direction" was what I was referring to in the original post. Basically there should be a specified amount of radial play when a specified amount of force is applied.

harmonic dissonance?

I have not driven the car with this flywheel. Previous owner installed a lightweight flywheel and 6 puck clutch combo, which is not very drivable for my sister. Reinstalling stock components- original clutch and flywheel have about 25k miles on them

If it makes a ton of noise engaged at low RPM's then it's probably no good, but it's not going to change the drivability. I've never seen them 'go bad' though... since they are typically not able to be resurfaced your not going to be on the same flywheel long enough for it to 'go bad'.

Keep the lightweight flywheel and get a O.E. style replacement clutch

I have a new OE Flywheel... NEW never installed.

lightweight flywheel with a full face clutch disk provides a better driving experience

I just had my flywheel replaced with another OEM DM flywheel. Nissan was trying to address a bouncing tachometer and thought maybe it had something to do with it. The answer was yes and no. While my tach doesn't bounce as much, it still bounces. But it still contributed to added movement in my tach and I could audibly hear the engine oscillating prior to the replacement. My clutch wasn't slipping and Nissan confirmed that. I think the flywheel was just beyond the standard radial movement. Otherwise the car drove fine.