[Brad Winder]

Sometimes Philco did use a thin gum rubber washer between the chassis and the cabinet, but usually only in higher end sets. The exception was the 39-42 era, when most of the larger chassis used special rubber "feet" in the corners of the chassis.

You could put thin rubber washers under the power supply/output chassis, as it wouldn't hurt. I can't say for certain that Philco did put ones in the 38-690...I'd have to take mine apart to remember. Lol!