this is the resistor in the bias point? if yes,you are not supposed to adjust the bias correctly.check the value of this resistance and change it.it will affect your sound.be sure to use the same brand.
When a power tube shorts out on a SF amp it will most often take out a resistor and a fuse. Subsequently you cannot bias the amp until you replace the resistor. Its happened to me 3 times in 10 years - Now I only use rugged tubes (SED's).