Vintage Casio Casiotone MT-40 - Great Condition

Description

Vintage Casiotone MT-40 in great condition.  Wonderful 80s tones and beats - the fills are hilarious.
See link below to YouTube video for a demo of basic functions.
Cosmetically, it looks great - some wear, but not much.  It is an ivory color - I'm not sure if it was originally white and has aged to its current color, but if it did, it is very even and the bottom color is not drastically different than the top.
No adapter, box or instructions.
The volume and the rhythm/bass volume need to be cleaned or replaced.  Both are scratchy and cut out as you turn them.  This is especially the volume knob, which is difficult to get to a level you can hear it.  Once you find a level (typically on the louder side), it is stable but if you move the knob again it will cut out.  I didn't attempt to clean anything myself as I don't want to open up the case and damage anything.
The battery compartment is clean but the foam is falling apart.
Please let me know if you have questions or would like additional pictures.
Thanks,
Alex
https://youtu.be/8YOuo92hFKc