Richard,

Another thought on your issue.   There have been firmware updates to the 
tuner over the years.  Since it is a used tuner, perhaps it needs a 
firmware update?    I think the firmware version shows up on the power 
up message on the tuner's display..   The latest version is on the MFJ 
site.   I've never done it, but firmware is  installed via the 9 pin 
serial connection on the rear of the tuner.

What brought this to mind is a faint memory  of some Kenwood users 
having some sort of problem with this tuner years ago.    I really don't 
remember what the problem was, but some were resolved with firmware, and 
some had to go in to the shop for  some chip replacement.

Just another thought.

73, Steve KW3A