Early versions of this hf transceiver got some issues with bad solder joints and bad connectors.
Also the pll has a notorious status.
This unit has a high serial number and lacks all this issues.
Due to her age the battery from the sub display has to be replaced. Easy to check when the sub display is malfunction.
To replace this battery just remove both covers and loose both srews from frontpannel so it can be bend forwards. Behind the subdisplay one can see the battery. A CR2032 battery is perfect as replacement.
Note: to avoid damage on connectors, do not remove this board.