Okay, your problem is with the check_command field. It should read like this:
Then, in checkcommands.cfg, you'll need this:
command_line /usr/local/nagios/libexec/check_nrpe -H $HOSTADDRESS$ -p $ARG1$ -c $ARG2$
Then, in nrpe.cfg on the remote host, use the first definition of the check_disk1 command, editing the path to suit the partition you're trying to check. Comment out the second check_disk1 definition. Then restart NRPE on the remote host and Nagios on your Nagios machine. See what happens.