With the tube switched in it is doing something, but how much of what is the question.

Totally agree with Doc on swapping the tube with any of the variants he suggested. Normal design has these types of tubes a cathode biased or self biased so there is nil need to set the bias on each change, they will correct themselves. Typically it is only output power tubes that need biasing adjustments done by a amp tech.

I doubt you will hear any tonal differences, but you will most likely hear gain changes with different tubes. Actually it makes me wonder about your gain structure and if you are driving the tube hard enough to generate some level of overdrive sound when the tube is switched in. While a clean bass is the most popular option an over driven tube bass is popular in some genres of music which I'd suggest is why the tube was included in the amp in the first place.

Just power down the amp when you do the swaps

And have fun...