Spider V 240 Mk1 combo making crackling noises

[rickofthemountain]

My Spider V 240 combo has recently started making crackling noises and is basically not usable. It seems like it's most prevalent when I plug in an electric guitar - whether it's single coils or humbuckers. My acoustic with an installed LR Baggs piezo/mic pickup seems to have less of an issue with the crackling. It happens mostly when I strum or when the input to the amp is at it's highest. As I let a chord sustain, the crackling diminishes. The first thing I did to troubleshoot was wiggle the input cord - this had no effect on the crackling whatsoever. The connection seems be be solid. I tried different cords - I use nothing but Mogami silver or gold. I checked both guitar jacks for shorts as well as the cables on another practice amp I have. I did a factory reset and got the same result. I randomly scrolled through effects and played and got the same result - it doesn't matter if it's a clean or high gain effect. I also scrolled through the effects and toggled gate, compression, anything on and off - and also got the same result. Headphone output has the same result, so I don't think it's a speaker issue either. I also connected my PC to the USB input on the back, and it played audio with no problems, so I don't think it's an output issue. I bought it in 2017 I think, and has the latest firmware updates and checked it just today. At this point I'm thinking it's an electronic issue at the input path. Anyone have any similar experience with this, and was it resolved?

Thanks in advance for any help.