Currently Being ModeratedSep 4, 2011 12:25 PM (in response to pyrospade)Re: curious what i should do with SV HD100 malfunctions
Personally I would recommend taking the amp straight back and get your money back. This particular head seems to have a problem which is probably why it was so cheap. It's possible it's up to four years old and will be well out of warranty. As a second user warranty is probably not available to you anyway from Line 6 unless you have the original purchase receipts and the original user has not registered the amp in his/her name. Spare parts for this amp may be scarce too.
You shouldn't have too much difficulty in sourcing a good and reasonably reliable Spider Valve HD100 MkI head on eBay or elsewhere (better if you know the history and the seller pretty well).
you shouldn't attempt any repairs yourself unless you really know what you're doing and are well aware of the dangers of working inside the chassis of a live tube amp. You could end up killing yourself as the worst case scenario - seriously!.
Just take it back and get your money back would be my advice.
Currently Being ModeratedSep 4, 2011 10:46 AM (in response to Nick_Mattocks)Re: curious what i should do with SV HD100 malfunctions
I would second Nick's suggestion totally.
Currently Being ModeratedSep 6, 2011 11:23 AM (in response to pyrospade)Re: RE: curious what i should do with SV HD100 malfunctions
I'd third Nick's suggestion. It's a used amp (no Line 6 Warranty on it); definitely sounds like someone (whether it be you or another potential user gear purchaser) will need to put more money into getting the unit serviced before it's up to spec again.
If you have a chance to get your refund from the store, it might be best to do so and keep looking for a different amp in better condition... taking into account your location and the reality of not have any Authorized Line 6 Service Centers in your area.
Best of luck in making your decision.