Need help with cleaning a Resonator

I have a Mya Moe Resonator that the metal disc needs some cleaning. There are some marks I could feel with my fingers (feels like dried residue of some sort). I tried to use a moist cloth and polish with a dry cloth but the marks are still there. Are there any special agent, detergent, or solution to use on a Resonator disc?

Thanks.

The thin aluminum of the cone will withstand typical solvents, so feel free to use Windex, acetone, alcohol or the like - just rinse thoroughly with water. A dried residue might be wood glue, so soaking in water might help. Strong acid or base would be a no no.