As this appears to be a musical instrument not a camera, further information may be forthcoming if you post this query in a forum dealing with such items.
YOu can disassemble the machine and clean the switch and resolver the connections to the circuit board, but it would be easier to call Roland and get the info for the nearest service center in your area.
If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/ Search the site by type in the "brand name" of your device, in the "Search box at the top right of the Homepage" to get gathered related posts.
And what is your question about it?
Most can be answered on the ROland site or from their customer support staff. Here is the link-
Roland Company Contact Us Contact Us
There is probably both a global volume and individual program violume as well. One or both may have reset to a lower level and need to be turned up. It's also possible that the general output has a setting for line level or instrument level, which may be software controlled. Take a look through your manual to find these settings and adjust to suit.If all else fails, contact Roland Customer Service at this link for help.
Roland Company Contact Us Contact Us
Will probably need to be diassembled and cleaned. Either a sticking key or a compromised contact on the circuit board. Any electronics repair shop should be able to fix this.
