You just confirmed what I said about the MFJ being touchy. It's actually ridiculous to use a test instrument that is.The Rig expert frequency is directly entered and can be change by moving the cursor on certain screens or by the up/down arrows and always stays locked on frequency.
The point I made about the Rig expert is that you actually get a visual graph of the whole band and what your antenna can do without having to turn a quirky tuning knob.
Also the Rig expert also goes a step further and has a USB computer connection and software to print complex information like Smith's charts and other information.
When you compare the visual graphs with scanning and all the other features against the MFJ 259 there is no comparison.
Look at the user selectable different screens which are lighted for easier viewing and look at the information you get with the Rig expert.
Below you see some scanned screens showing just SWR by itself,SWR bandwidth, Full analyzed info on your antenna, Quick multiple SWR readings for multi-band antennas, R and X scanning, and the easy to use menu screen where you preset the analyzer for what you are working with.