Tubes For Dobro Amp?

anyone know where to find tubes 4 a dobro brand amp.real little.kinda rusty but maybe will work.the one bad tube was busted during the move. has been under a bunch of other junk in a old storage building for who knows how long.also salvaged old gibson amp water damaged case so i stripped off the rotterd particle board and got it to work. the gibson aint really old cause its solid state but the dobro amp has to be 30 40 50 yrs back.