Tweed GA-20s are rare in the UK.  This amp is like a souped up, two channel version of the Explorer.   Same tonal foundation but so much more going on.  The two channels run on different tubes and have quite distinct sounds which make this a great amp to play.  Stable but versatile. Both inputs on Channel 1 get a triode each, whereas the inputs on on Channel 2 share a high gain pre-amp pentode.  This gives the 2nd channel a very distinctive tone, quite unlike the now ubiquitous 12AX7.  Two 6V6 power tubes in push-pull give this amp plenty of warm fuzzy power.  Both channels are so great that it's impossible to decide which one to plug into.   An AB pedal is arguably all you need to get every sound you need when you gig this.  

We've changed out the P12R with a big magnet Warehouse, louder and with a warm low end, it's a great option..  Other than that and a couple of caps, all original, including the handle, footswitch and possibly even the badge.  No rust on the control panel!!! Inexplicably, 1/4" has been removed from one of the back panels.  Requires a step down transformer to operate this in the UK.