Originally Posted by JoeD
Sounds like one of the fuses had a poor connection. Some times the clips that hold the fuses become stretched and do not grip and contact the fuse properly.
I would say Joe is correct about there being a contact problem in the main box. And while it could be just not getting proper contact with the fuse it could also be where the clip for the fuse is attached to the box. From the description and age of your equipment you can have many issues as described in all the previous posts. My concern is if it only took pulling the fuses out and putting them back in to "fix" the problem then you obviously have a loose connection, probably in your main panel, that will now heat up because you are drawing current through it. Monitor your main often to be sure you don't burn the place down till you can get it fixed right.
I bought an old home once knowing one of my first priorities would be to replace the electric service. On the morning I arrived home from work and the power company was coming to change me over to my new service, I walked in the back door and smelled something really hot. I checked my main service boxes (two 60 amp boxes side by side) and found a fuse socket sizzling and glowing red. The girls had two minutes to finish getting ready for work/school before the power was shut off. It can and does happen all the time. I went to a fire call on an old home and found the only reason the building was not burning was because the panel caught fire and melted the plastic water line directly above the main box and extinguished the fire before it could get rolling. Unintentional sprinkler system.