Need advice

yes likely the tube, try a good replacement tube 

@jjss49 

+1

Always the first place to start, most likely. With Audio Research gear I don’t tube roll. I’d get a brand replacement or similar. But that is me.

https://www.tubedepot.com/products/6dj8-ecc88

pay for triode matching and low noise graded... have fun

Thank you for your help.

I ordered Electro-Harmonix 6922 EH Gold Pin from Tube Depot as you suggested.

More Help!

Received electro-harmonix 6922 gold tube for Audio Research LS2B MKII , now need to know can I just install it, or do I need to set Bias etc?

I read online about bias adjustment and gain adjustment but can't find a service manual online. 

Just plug it in. Give it at least 24 hours of play time before you reach any conclusions as to 'sound'. 

In most experienced users minds there are many other tubes that sound better than Electro-Harmonix.  For 6922s try the Phillips from Holland.

Good listening,

Robert