Melotron can change a sound more if you change a tape rack.
This video explains a way of the exchange of the tape rack.
1 : Take off a lid.
2 : Take off a keyboard. The keyboard is fixed with four screws.
3 : Take off a metal plate for tape guides.
4 : Take off tape. The tape is fixed with four screws, too.
5 : Lift a tape rack and take it off.
6 : Put the another tape rack (A chorus, an oboe, the sound of the vibraphone are recorded with this case).
7 : Install each part in a reverse procedure.
Will it be easy than you load a sound in memory?