I tried my hand at building a Webber Kit for a 5E7 Combo. I got through the main board and got a little intimidated when I got to the power section so I brought it to a local amp tech who finished it for me. I had it for a little over a year and gigged with it a few times and sold it to a friend of mine. I ended up buying it back and it has developed an odd issue. After playing the amp for 20-30 minutes when I turn the volume pot on my guitars up or down, I get a scratchy sound like a dirty pot... this does not happen with the same guitar on any other amp. If I turn it very slowly it is less noticeable if I turn it fast it is much more pronounced. I have switched out pre-amp tubes which did not fix the problem. It seems like it has a bit less headroom than what I remember but it's possible that may be me and not necessarily the amp. So the $64,000 question, why would a sudden change in my volume pot cause a static or dirty pot kind of sound? Any help is much appreciated.