You're very welcome. In addition to the information stated above.
Follow this procedure.
1) Check (Ohmmeter circuit) inside
your unit for defective resistors, there is no adjustment potentiometer inside specifically for RX1 scale.
2) short out the banana jacks with a jumper, On RX1 scale, your test leads have more resistance than one ohm. If your meter zeros with jumper. Then you must subtract the resistance of your test leeds on every measurement you take on RX1 scale.
3)Check battery terminals for corrosion or loose connections because... On RX1 scale Independent of "brand new batteries installed"
more current is used (Sourced) than any other scale on your meter.