[Elecraft] K3 SUB RX no audio

[gt-i at gmx.net]

Hello group,
since some days I experienced a malfunction with the SUB RX. When I
engage the SUB RX, there is no audio. I can hear the typical relay
clicks. A power cycle sometimes seemed to cure the issue, but IIRC there
were also occasion when this did not help.
Anybody had the same issue, any ideas?
73 mni tnx Gernot DF5RF