Seems like there are several stations and they may be off-frequency. Closer to 6860 kHz USB but the one I'm listening to right now (1340 UTC) sounds best on 6859.5 kHz USB mode. So maybe that is their frequency, or maybe 6859.6? Usually there's some sort of method to their madness (or madness in their method).
I put 6859.5 kHz in the thread title because that seems to be the best frequency for actually tuning these guys in. Minor QRM from nearby chatter. SIO 222.