I'm thinking this is a permanent change from slow dash to fast ditter.
It's again very strong right now in this capture from KFS, ditting away on the right of the picture.
These, the 2 second dasher and the fast ditter, do not appear to be the same signal. Instead it looks like the fast ditter has shown up on very clsoe to the same frequency as the dasher, and the ditter is typically the stronger signal.
Prior to today I thought that because the propagation of the fast ditter appears different from the 2 second dasher. The dasher was more condition impacted, I mean when conditions were very good (based on multiple signals) so was the dasher signal, but when conditions were very bad so was the dasher. I might go for days not seeing / hearing it, and then watch it slowly fade up as conditions got better.
The fast ditter has been more consistent in level, almost always being heard, day or night, at my location.
Also, I could sometimes null the ditter with a loop and start to hear what I thought was the dasher under it.
But today I am more sure. It looks like the dasher has shifted down in frequency, more near 4096.1 kHz, and as I type this I can hear both the dasher and the fast ditter. Also, it appear the 7997.2 dasher, possibly synchronized to the 4096.2 dasher, appears to have shifted down to about 7997.0.
T!