Nice set.

ONly caps Id be changing on this set is the black beauty on the horizontal osc. board. In my experience, Ive never had problems with the paper axial electrolytics. I worked on a 7 last year and it was loaded with paper wax caps which had to go. Ive never worked on a 9 before. Im glad to see it was improved with basically all mylar caps.
Every so often, you will have a bad mylar, but its not worth recapping the entire set for. Depending on the trouble symptoms of the set, check the appropriate stages and replace as nessisary. A capacitor analyzer is an excellent peice of equipment to have. The heathkit C-3 works perfect and is cheap to buy on ebay. Its user friendly too.

For best reliabilty especially in equipment that runs a lot...we like to change all electrolytics more than 35 yrs old or so. An ESR meter is also a good tool to check electrolytics and I would recommend checking ESR so you can spot marginal caps if you don't replace them all.
Have had one too many cases of shorted electrolytics to trust old electrolytics too much.