Recoverable Memory Error - Next steps?

Good Morning,

Over the past couple years, we've seen a number of "Recoverable Memory Error" alerts from our out-of-support PS4000.

They were a couple months apart, and now seem to occur every month or so.  I'd like to be pro-active and replace what needs replaced.

Error:

WARNING 9/26/2016 8:37:35 PM CINPS4000 19.3.0 | 19.3.3 | 19.3.16 | 19.3.24 Recoverable memory error on CM in slot 0 | Initiator of the data request was (0x1): CPU1 | Responder to the data request was (0x7): Memory Controller | Correctable memory data ECC error.

WARNING 9/26/2016 8:37:40 PM CINPS4000 19.3.0 | 19.3.2 | 19.3.16 | 19.3.24 Recoverable memory error on CM in slot 0 | Initiator of the data request was (0x0): CPU0 | Responder to the data request was (0x7): Memory Controller | Correctable memory data ECC error.

WARNING 9/27/2016 8:55:03 AM CINPS4000 19.3.0 | 19.3.4 | 19.3.16 | 19.3.24 Recoverable memory error on CM in slot 0 | Initiator of the data request was (0x2): I/O Bridge 0 | Responder to the data request was (0x7): Memory Controller | Correctable memory data ECC error.

WARNING 9/27/2016 8:55:09 AM CINPS4000 19.3.0 | 19.3.2 | 19.3.16 | 19.3.24 Recoverable memory error on CM in slot 0 | Initiator of the data request was (0x0): CPU0 | Responder to the data request was (0x7): Memory Controller | Correctable memory data ECC error.

What exactly do I need to purchase here?  RAM?  What sort of prep and downtime should I expect? 

Thanks