Resolved with the following..
#restart process snmpMasterStep 1: terminating process snmpMaster gracefully ...
Step 2: starting process snmpMaster ...
Restarted process snmpMaster successfully
Now both cacti graphing and netsight (XMC) can see the switch again. Also the command sh management displays in its entirety, rather than displaying 2/3rds hanging for 10 seconds and then displaying the rest.
Weird issue, but I'm thankful for the modularity of the linux core and the ability to restart a process without taking an entire switch down.