I believe it is a combination. The radio needs a broadcast signal, strength of what the radio responds to being modified by the sensitivity selection lever. That part of the circuit is what the large seeking bar on top responds to.
When a specific button is pushed part of the automatic seeking circuit is bypassed. Each of the individual buttons has a sliding contact which makes a connection to a copper foil trace on the phenolic board that holds the sliding contacts. Another contact on the end of the dial arm slides over the sliding contacts to complete a circuit going to the tuning circuit. That completed connection triggers the stop tube so the pointer stops at the selected station.
If you flip down the thin door above the individual buttons you can see the sliding contacts and phenolic printed circuit board that holds them. One probable issue is the copper traces on the board have oxidized and lost good contact with the sliders. Another issue is the contacts on the individual slides or arm assy is also dirty or has been damaged and is not making good contact as the arm slides over.
There is a schematic of the
55 signal seeking radio in the literature archive. As I recall, the 56 power supply is slightly different but the tuning section is the same.
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=265424