My MKII is starting to cut in and out. I'll have strong volume, them in an intant it's about 1/2. It will jump like that. I have had this amp for almost 1 year and this started roughly 1 month ago. I checked the tubes, they appear seated correctly. Could I have a tube issue or is this a known issue with the amp and it's going bad? This is especially bad due to I am in a working band that is out every weekend. Most Line6 shops tell me 4-6 weeks, which is completely unacceptable. Any advice/help?