Funky little problems on PSR 2000

[jazzump]

Out of nowhere, settings that I’ve had for years on tunes have suddenly disappeared. Specifically, main and layer voices on arrangements, that would change on different parts of the arrangement, ie verse, chorus, bridge, etc. they now default to grand piano on the main, and live strings on the layer. Suggestions?

 

[happyrat1]

Does it have a replaceable battery to keep the memory?