Looks like a mini scout, has just one knob on back. Tube is 8417.
Tune for max output and cross your fingers.
if it only has 1- 8417 tube in it ,then that screw is your deadkey adjustment .it is setup like a modulator .
in other words you dont "tune" it .you just adjust your deadkey out the amp and let it swing .
all single 8417 tubes i ran i would set it for 30 watts deadkey out the amp and let it swing .should swing over a hundred depending on input .
you can run 4 watts in safely,then adjust the screw for 30-40 watts deadkey and let her rip.
same setup like a jb150
Peak or deadkey?