Rockola 1454 selections

Hi
I have a Rockola 1454 that does not select no 6 , 46 or 86 this has only recently been discovered as they are b sides and seldom selected, I have spayed behind the buttons but to be avail, I’m not 100% sure how long these have not worked but they do make the correct selection noise but nothing else.
I’m thinking it could be the selection assembly but have no idea of how to strip and clean as the handbook is not clear
Any help would be great

Hi,
when you select 6, 46 or 86, the pin selector move or no ?
Best regards