Hello this is a question in regards to my Philco 39-341. The radio sounds great and loud on shortwave, overpowering the speaker at times and not too bad on our hometown AM broadcast band station but all other AM stations are real low in volume...however when I touch the grid or put my hand near the grid cap of the 6A7 tube located between the 2 #78 tubes ,the volume goes up tremendously and sounds like it should....I was told by a gentleman that the AM antenna coil trimmer needs adjusted maybe.....I have no idea where that trimmer would be.... and there is a schematic for a Philco 39-40 etc.. etc... and other similiar models but with pushbuttons.Maybe I just need a much longer antenna and a ground wire to cold water pipe but I am wondering if something else is going on here....

By touching the 6A7 grid you have bypassed the antenna coil. The coil is open or bad connection at the AM/SW switch.