The last few weeks I've been playing my guitar the sustain has just disappeared, don't know why, this happens especially on the higher strings, the clarity of the notes has also gone somewhat. My guitar is a MK Patriot Custom, and the strings have recently been changed. I had my amp checked by a tech so definitely isn't that, and have tried it with a few good cables. I have a feeling it may be something to do with the input jack because it seems a bit loose? Or could it just be a bad set of strings?
Well, check the input jack for damage or bad solder joints, but I think it's probly the strings.
Most probably a bad set of strings. Also, do you have active pups? If so, try to change the batteries.