Each vintage saxophone brand and model offers unique challenges from setting up the table keys properly to adjusting and regulating the multitude of perm-adjusters and set screws. When notes won't play on a saxophone it's almost always due to air leaks. The tan/brown leather pads under the keys are supposed to seal the air from the tone holes. If a pad doesn't seal well, the saxophonist has to blow harder or squeeze the key until it seals. For more info regarding musical instruments rent or repair, go through
this page of Webmusic. A good quality saxophone that is repaired properly should play as well as it did when it was new. And a good saxophone that is maintained properly should last a lifetime.