[BILL]

I believe you'll find that radio is a DELCO Studebaker quit buying it's radios from Philco ,I think, about 50 or 51 one of those years it's possible to find radios both built by Philco and Delco for Studebaker, If this is an original 57 Studebaker I have the Delco service manual and most likely the parts you need I think I'd look first on something else being the problem ,have you another power supply? Disable your power supply and aply 250 volt to your B+ most of the problems are in the power supply on these old radios, also check the voltage on your IF the primary will have the high voltage the secondary will be low , I had a 56 Ford radio{MOTOROLA} that checked out OK with no power with power it would leak high voltage to the secondary, replacing the IF took care of it , but that is a rare problem, usually you can see and hear an IF ark if they are shorted, I have found on these two piece Delcos 55-57 Chevy is almost the samething the lead between the two units is shealded with a metal covering the fabric coated wire will become fraded and short out , check that also: BILL