Picture will help too . Amp If you are not original owner , check if fuse ( on the back ) is the right one The Tube Charts are notorious for being incorrect, especially in that era. The 1970 serial #s for the Twin Reverb run A21400 to A25600.
Suspect yours was produced in the 1st half of the year. '70 to the AA270 circuit, but this wasn't put into production until late 1970.
The serial number stamped in the chassis is A23373-107.
It has 117 volts, 2.3 amps on it I believe, silverface with black cloth, AB763 on the tag.
Not only did Stewart suggest a more suitable valve for the tone I was after, we had a really enjoyable chat and he give me some really useful tips for future fault finding.