Marshall Valstate 100r - No distortion

[DonJoe]

Saludos:

By accident my son's cat pushed the amp to the floor face down from top of a 212 cab.
The guitar cable was still inside the input socket. It tested the amp afterwards and there was no sound.
So I pulled the chassis out and found that the rear contacts of the input socket where dislodged from the main board. I dismounted the input socket and soldered all contacts making sure that all connections were well done.
This time I tested the amp and the clean channel was loud and clear, but all I got from the overdrive channels was a clean sound no distortion. All other controls gain, volume, treble, mid and bass seem to work OK on both channels, but then again clean sound no distortion on both.
It appears to me that the preamp tube 212AX7 might be broken from the shock.
Please let me know if a broken preamp tube might be the cause of not getting distortion on the overdrive channels.
I also want to know if there is any procedure to replace the tube or should I just take the old one out and replace it with a new one.
My son’s guitar has EMG81 and 85 pickups. What would be your recommendation for a replacement tube? Should I use Tugsol, Svetlana, Ruby…?

I'll appreciate very much any advice you can give me with this problem.

[J M Fahey]

Check that the tube filaments still glow, and that the silver plating of the glass has not turned cigarette ash white.
Buy any 12AX7 you like, this is a no nonsense forum which prefers not to rate products on Mojo and other inmeasurable effects.
Our colleagues will certainly recommend a couple brands based on reliability and consistency.
Be certain that Marshall, like any big scale manufacturer, will go for an easy to purchase, reasonable quality, reasonable price one, to fit as Original Equipment.