Recto Pre has an issue

[RectoStudioGuy]

My Recto Pre sudden started making an odd static-like sound immediately following hard struck chords and somewhat after lead passages. I've never had this issue before and it seems most prominent on the "vintage" voicing setting. Ideas?

 

[Jackie]

I'm probably stating the obvious here, but check the tubes, they're the most frequent culprit for all sorts of unwanted noise.