C band LNBF? Must be if you can receive the SES mux on 3740. Do you receive DW 2 Radio?? ???
Are there Numbers, band or L.O. info or model, on the LNBF? Should cover the Ku band 11700 to 12200 with L,O. 10750
Setting your meter to the mux your after, 12140 V 20000, which also 'matches' the dish/LNB (lnb settings set to: L.O. 10750) might get you desired results.