Hi Aaron,
thanks for that piece of information. I will do this shortly. I've just spent the last hour with our F5 support contractor and he was quite confused as well. We created a small shell script on the BigIP itself based on a example off the wiki and when run from the command line it works, that is it connects to the URL and does a grep for the search string and if grep finds it returns true. We then created a new external monitor and specified this script, but the pool status still stays as a blue square. As a last resort we changed the health monitor for the pool to be tcp, and even that results in the same behavior.
I'll enable debug tonight and do some tests and post the results.
Many thanks for your help on this and all the other issues I've posted here that you have replied to.
Regards
Craig