Greetings, I purchased a Spider IV 75 off Craigslist and for a year, it served me quite well. When I turn the amp on now, I get a loud static like hiss. The hiss is present with both volumes turned completely down and it hisses even when a guitar chord is not plugged in. I did a reset and the static went away while during the reset process. Once the reset process was complete, the hiss returned. Any guidance would be greatly appreciated. Thanks!