19J6 tubes - availability and/or substitution

Hello all :)

I have a whiplash starving student amplifier that uses 19J6 tubes.

For around a year I have fought with a tube that makes noise.  Its a fairly constant crackly hiss.  It goes away for the most part while music is playing, but in quiet portions of the song I can hear it.

I also use this amplifier for all of my computer use so frequently I have my headphones on with no sound coming through them.  It is quite annoying to have this hiss.

Now my problem.  I can't find 19j6 tubes anywhere.  Is there a source I don't know about?  Could I possibly use a different tube in this same socket?

I love my amp, but the noise is really starting to get to me.

I tried ordering from tube depot and they were back ordered for 3-6 weeks or something like that.  I've read other posts that they never show up.

I saw someone talking about a 6j6 tube.  Everything is the same physically, but the voltage and current are way different.  It plugs into the same socket...can they be used in my amp without causing harm?

Mechanical Data

Bulb .......................................... T-5 1/2
Base .......................................... Miniature Button 7-Pin
Outline ....................................... 5-2
EIA Base ...................................... 7BF
Mounting Position ............................. Any

Electrical Data

Heater Voltage ................................ 6.3 V
Heater Current ................................ 0.45 A
Maximum Heater-Cathode Voltage
Heater Positive with Respect to Cathode
DC Component .............................. 90 V
Heater Negative with Respect to Cathode
DC Component .............................. 90 V

vs 19j6

Mechanical Data

Bulb .......................................... T-5 1/2
Base .......................................... Miniature Button 7-Pin
Outline ....................................... 5-2
EIA Base ...................................... 7BF
Mounting Position ............................. Any
Electrical Data

Heater Voltage ................................ 18.9 V
Heater Current ................................ 0.15 A