Emblemdhc

Sir there is only one DME tuned by two GNS 530 for selection NAV1 and NAV 2 there is sperate switch For indication  both PFD  and Bendix king indicator KDI 574  So first we tune DME   by No.1 GNS 530 there is  No distance and no audio tune heard Sometimes I noticed there is audio tone and no distance on KDI 574 And next step we tune DME by no.2 GNS530 there is distance on both PFD  and Bendix king indicator KDI 574  And audio tune heard  Next step now we Swap GNS 530 with each otherNow swap conditions And next step we tune DME by no.1 GNS530 there is distance on both PFD  and Bendix king indicator KDI 574  And audio tune heard  And we tune DME   by No.2 GNS 530 there is  No distance and no audio tune heard   But after 3/4 power cycle  DME Not showing distance and no audio tone by both GNS 530  Sometimes it show  distance on 1 and 2 selection by GNS 530  But sometimes not This system is only one of our aircraft not in any other so we can’t swap anything from. Another aircraft I don’t understand what to take next step now