You may have a cold solder joint. Just fixed an intermittent of similar nature in a Philco 66 (restoring for my inlaws 50th anniversary-both born 1935).<P>------------------<BR>

That may be normal, as the loop may be supplying AGC bias to that grid,;See iflow end of lop goes to AGC bias line. With no loop, there may be no DC connection to radio; the grid itself charges up negatively,due to passing electrons hitting it; with no path to "leak" off, it gains a negative voltage. When you touch it, your hand discharges the tiny (-) charge, and it works again(Human hand grid leak!)try 5meg to ground instead, or connect loop. You can't adjust trimmers without the loop anyway..they will be wrong.<P>------------------<BR>