Spooner wrote. Typically when old; what parts need replaced right at the start? or do they wear pretty well? On the bandsaw the rubber tires come to mind. Do those dry up and crack and go bad? Jointer blades? Replacements? Any other thoughts you might have before I begin looking into those?
1) Any SPT you should not assume it is in good operating shape. Critical element - bearings. Check all bearings. Clean and spin them, if they don't spin freely or make a ticking sound, replace them.
2) Read the manual for each SPT. They will give information on expected life of items like blades, tires etc. Blades can only be sharpened until they reach a specified dimension, then must be replaced.
As these machines get older, people are starting to rebuild them from older machines. Keep in mind that the jointer in particular is cast and machined as a unit - the two halves are mated at the factory. A used jointer rebuilt from parts could contain two dissimilar infeed and outfeed tables, which will not fit together correctly. (This has happened!) So you should check squareness and accuracy of any tool before buying.
Also look at bushings. These tend to wear over time, often becoming ovalled. They should be replaced if there is sufficient wear. The scroll saw arm has multiple bushings that should be checked.
Shafts holding bearings and or riding in bushings may wear as well and should be checked similarly.
Lastly, any gears should be checked for wear on the teeth.
