Hi.
I would start to check the board for unsoldered relays pins. It looks like one coil is staying non shorted all the time.
Second, I would check all the relays are reenergized in reset mode except middle C switch relay, it should be energized.
In third I would check the power measuring on 28 MHz and if that value is wrong and less than value on 7mhz I would change the diodes .
This tuner will not work properly on 50 MHz. Too much it's own reactances.?
