I have a Bemoaster 4400 I purchased as a backup while I have my other amps on the bench ready for recapping.   It sounds fantastic however it looks to be in rough shape - it's missing the Volume slider  and the mechanical buttons for  Mono, Linear and Loudness - are troublesome.  In order to get those buttons to engage, they need to be depressed a few times and while depressing I hear static and scratchiness through the speakers.

I got tired of looking at my fuzzy, scratchy, water ringed, beautiful sounding amplifier so yesterday afternoon I took it upstairs for a good cleaning.  I opened it up, checked the solder joints and blew everything clean with an air, next I took the front slider plate off and sprayed CRC cleaner in the buttons while pressing them on and off.  I also took some #00 steel wool and lemon oil to the wood on the cabinet. The unit really cleaned up well.  

My Issue:   After cleaning the buttons with CRC, they work well and there is no more static however the bank of buttons - Mono, Linear and Loudness - no longer engage by depressing them from the front.  If I open the bottom of the receiver, I can persuade them to engage using small screwdriver - pulling them out slightly while at the same time depressing the button from the front.  

Mechanically and electronically  they are working when engaged however it appears that the slot where they protrude from the front of the receiver no longer provides enough travel for them to fully engage. Did something shift?  Are the tolerances so close that if they move slightly the buttons won't engage?  

Also the button mechanism doesn't appear to be very accessible, without taking a lot of things apart. 

Appreciate any help.

p.s. This isn't the first time I've "fixed" a B&O something and had something else go wrong or wound up with extra screws or nuts wondering where the heck they came from.   They do have personalities.