you *should* backup your preset anyway; you have 2 ways to do this:
-use Vsig editor on a PC and store them to the hard disk (best)
-use a PCMCIA card (worst)
The battery is soldered to the circuit. If the unit works well, the battery id fine.
When you start having all sort of warning/error messges, and frequent checksum errors messages…then the battery is about to go.