RCF 8004 Castor Install & Warehouse Light :: Warehouse Talk 

I have the same 8004 subs and I found that if you engage the locking mechanism on the wheel it usually stops that vibration you are experiencing.

Maybe put a rubber strip at edge to protect it from scuff

If you set the breaks on it it would reduce the noise. if you have the kind blue Wheels that also stops it from turning the bearing then the noise is Totaly gone. Atleast that works for me.

Lol, you must be careful with subs 😂