Probably bad DMF?

[WrenchWhore]

Man, if only those ZF5's had an inspection cover you could remove to check the flywheel springs. It would be cool if you could drill a hole is something none structural and look with a borescope. I did this with a cheap amazon USB borescope connected to my laptop (huge screen) and was able to visually diagnose piston slap in a motor with only removing spark plugs and looking down in the cylinder. With the amount of racket it's making it should be painfully obvious if you COULD look at them.

 

[Nero]

What I've done in the past is just remove the lower cover, and grab the pressure plate and rotate it back and forth, if the flywheel is bad enough, you'll see it rotate. That's how mine was, moved a good 3/8"