Right I've had one of these for a while and it's been absolutely fine with how I was using it.
Until I started getting this super load very high pitched feedback/squeal. Assuming it was the bass, as it happened right after I changed the body, I've changed the pickup and the electronics.
I've then proceeded to check everything!
While checking stuff I noticed that while the Suncoasts volume was off and nothing was plugged in it was generating this high pitched whine. Turning up the volume made it louder all the way until it sounds like its oscillating!
Same thing happens turning the drive up and down. Playing around I found basically moving any knob up or down makes it worse or quieter, but it's always there!
I've tried everything with the power too and it's still there.
The only thing I haven't tried is a complete isolated power (batteries).
I can obviously set the pedal as such it doesn't feedback while using it but then I wouldn't be using the sound I want it for, and sometimes it will still give me that gnarly high pitched squeal.
I'd like to stress that I've used the same settings on it for ages and one day I got this high pitched noise and I've just found out about it's whining yesterday. I've emailed Sales at suncoast but no reply yet.
If it is broken, then I have no way to replace it for £350 haha!