Hello JimS,
this definately sounds like a config issue. You may wish to take an SCF backup from the working device (unit 2) with the command:
b export
which writes an SCF to /var/local/scf. SCP this file off, change the hostname, non-floating IP addresses, failover settings etc to be valid for unit 1.
Then load the file to /var/local/scf on unit 1 and make it active with:
b import
See if this makes any difference, you also then have a backup of the system in a single text file. An overview of SCF files is available here:
http://support.f5.com/kb/en-us/solutions/public/8000/400/sol8435.html
Let us know if this helps!
Chris