I worked on a pair of KLH 6 of this vintage, once. I replaced the capacitors by removing the plate in the back and working through a small hole in the cabinet. I think it took a week to replace the capacitors. Painful process, forcing my hand through that small hole. I like this approach better. I am sure that it sounds just a good as mine. Who looks at the back anyway.
Sometimes we just need to step outside the box.