If the station selector shaft is not pushed all the way in or pulled all the way out when changing from the standard drive to the 60-to-1 ratio, the rubber drive wheels will not mesh correctly, and will soon wear to the extent of slipping. Customers should be carefully instructed on this point. When making a replacement of worn drives, the bracket which supports the drive assembly and which is riveted to the tuning condenser frame should be carefully examined. If this bracket is loose, the rubber drives will not mesh correctly, and will wear in a very short time. New drives will soon wear out in the same manner unless the bracket is tightened.
From the Philco Serviceman – May, 1934.
If the drive wheel rubber is too worn or cracked and dried out, there is a repair method of rebuilding the rubber drive wheels. This tip is on the Philco Radio.Com website and can be found in the Tech Section, “Rebuilding the Dial Drive Mechanism in Model 16”. This method also includes Models 34, 44 and 144 which also use the same mechanism type.