?With regards to SWR readings- are they being read on the tuner in use? I use an AT1000P2 and an AT600P2, both show SWR reading vastly different than my rigs, my amps and in-line SWR meters. The latter 3 are in close agreement. On some bands/antenna combinations, the LDGs are pegged, the rest of the meters show less than 1.5 to 1. No amount of cable changing or ferrites can clear it up.
Comparing the LDG to a 991B, the MFJ claims a wider range. I don't think there is anything wrong with your LDG, just asking it to do something it's not designed for.?
Mike N3PM