RFSpace SDR-IQ Question on Gain settings GNU Radio osmocom Source

Hello, I hope this is the correct list to ask this question. I have an SDR-IQ connected via USB to Ubuntu 18.04 and version 3.7.13.4 GNU Radio. I am getting data from the source at correct center frequency and sampling rate, however ... I am having trouble find 3 of 4 gain controls. I believe these to be the settings affecting the device gain: 1. RF Gain: -20, -10, 0, 10 dB. These I can successfully change via the RF Gain setting in the Osmocom source. It's good! 2. IF Gain: 24, 18, 12, 6, and 0 dB. This is a "digital gain" and changes a coefficient of the "6620 Digital Downconverter", which apparently is hardware in the SDR-IQ which does filtering and decimation. 3. Preamp Gain, via a "GN Code" of range 0-127, which goes from Off, and then a range of -8.08 to 34 dB. 4. A step attenuator with 0 and 10 dB settings. I got the above by examining the "SpectraVue" Windows application for the SDR-IQ provided by RFSpace. #1 is no problem, it works. What about 2, 3, and 4? So is there any hope of controlling these settings with the osmocom source? Regards, Greg R