[Mondial]

It seems that there may be some issue with the bandswitch sections related to the local oscillator. When in the pushbutton tuning position the variable tuning cap is isolated from the circuit and replaced with a fixed value cap. Perhaps there is oxidation on the switch contacts (section A8 ) which connect the variable cap to the oscillator coil?

There is an awful lot of switching going on in that osc circuit and any bad contacts may cause loss of tuning range.