If you go into cmsh and do the following, you will be able to see which healthchecks are failing, and (to some degree) why:
# cmsh
% device use sny02
% latesthealthdata -v
Once you know which healthchecks are failing, you can start investigating why. If it is not clear why a healthcheck is failing, you can look at the healthcheck script and see exactly what it is doing. They are in /cm/local/apps/cmd/scripts/healthchecks. You can also run a healthcheck immediately by using the 'device samplenow' command (e.g. device samplenow -n sny02 schedulers)