Flex-6400M Internal Tuner Behavior

I'm experiencing some odd behavior with the internal tuner on 75/80 Meters.If I go to a frequency above around 3.900 MHz the tuner will rarely find a good match. It ends up being well over the 3:1 max range of the internal meter. However, if I start at a lower frequency say around 3.800 MHz and tune I get an SWR match of around 1.1 and then I can dial up to 3.900 MHz and the SWR indication does not go above 1.4:1. At 1.4:1 and can engage the tuner again and it will drop it back to around 1.1:1 again. If I change frequency up or down by about 1kHz and retune no match is found.

There have not been any station changes for a few months. I'm using and end-fed antenna and until recently I have never experienced this behavior. It only occurs on 80 Meters. There are no problems anywhere else.

I would appreciate any thoughts. It isn't a show stopper but it seems very odd behavior.

Tim N9PUZ