Thanks Karl,
Didn’t realise I needed to add both the community string and version to the command as thought it would parse from the host itself. Used the following and working perfectly:
check_snmp -H 172.29.1.93 -C SuPeRsEcReT -P 2c -o iso.3.6.1.4.1.9.9.392.1.3.1.0