Well im not an expert in this field and before learnig, i use to do alot of reading, and most people tend to over react on tube swap, the tru is, and i learned this from an old old guy that had years of experience, as long as the tube has the same pinout, and the yoke has the same readings, youll be good to go, theres some precaution only, when you are giong to conect the tube at the chasis, to make sure you are conecting it right horizontal and vertical at the 4 colors conection, as sometimes those are inverted. I have sucesfully swaped 3 tubes with that technique. Good luck.