I have a valve amp I really like from the late 1960's. It is currently working well and it is quiet. Over the years it has had some repairs as expected but its circuitry (all point to point wiring) is largely original, which means that many components are c.45 years old. Is this a problem? Am I tempting fate in terms of reliability to keep so many original components in it? I like the way it sounds now, and I wonder if rebuilding it and thus replacing lots of components will change the tone/sound. Is there a trade-off between originality vs rebuilt; tone-I-like vs reliability?