Well, i got a Carvin X-100b about a month ago, i believe its late 80's, most likely 88

well, on the clean, when I first got it, it was nice and clean, perfect for what I wanted,
but now, for some reason, it seems distorted, anyone know why?
im using the head connected into my brothers randall cabinet, not sure what model, so idk what settings i should use on the back of the carvin, since it has the output percentage, the 16 ohms thing and all that, im new to all that,
anyone know what I should use, and if it would return my clean to its glory,

also, on the Graphic EQ, when i turn it off, it is LOUDD, and if its on, it goes quiet, but it didnt always do that, not as far as I remember, anyone know why that might be? and before I got the amp, I read the eq only effects the channel its set to, but it does this to both channels

sorry if I wasnt too clear with the problems, or if i left something that needed to be said out