You only use disc dampers on top-loading CD players, Marantz, Esoteric, Luxman and the rest is a big no, no, your only asking for trouble. They are no designed for these types of players in fact they go way back, some who made these types made a note of saying this.
A black hole went into my Marantz SA-10!
I always use a Herbies black hole II CD disc damper. It somehow got lost inside the transport. The tray is shallow as is, so it didn't take much for it to get knocked, and in it went! So I freaked out. I looked inside behind the tray with a bright LED flashlight. I didn't see it. Everything works. Tray goes in and out without any snagging. No skipping. I'm not not very mechanical and have no idea which screws to loosen and don't want to mess with it. It happened about 30 hours of listening ago. I use the Herbies black hole CD disc damper for 6 years. When I had my Sony 5400 ES it did make a difference and was repeatable. My GF agreed. I never did the AB comparison on the Marantz. Maybe the transport on it is not tweakable since they built it themselves. I know Steve Nugent here is a big believer in some kind of damping. Anyway its playing.