IC7300 EXTRA CLOCK BATTERY WITH LR2032, 3.7 V/40 mA

.

On the internet are various descriptions to replace the backup clock battery of an IC7300 by desoldering or cutting, connectors are disconnected, front plate is removed and the relevant pcb is lifted.
All that effort is not necessary if you install an extra rechargeable Li-Ion battery LR2032, 3.7 V/40 mA of larger capacity.