1400v seems beyond excessive for that tiny amp.....even 500watt guitar amps i work on only use 600-800vdc at best.

What is the number on the valve? as the first digits will confirm what the heater voltage should be.
e.g. a 12AX7 (typical dual-preamp) requires 12v heater voltage, while a 6L6 (output valve) requires only a 6volt heater voltage.

Is there only 1 valve or more?

I'd also replace all those hi-voltage electrolytic caps, they dry out and start conducting(shorting) DC voltages to ground.
You can remove the Negative/GND end off the chassis and measure using DC meter from the negative pin to chassis, if you read ANY DC volts, your cap is passing DC and needs replacing before it smokes/blows.

Hope it helps a little....
MM