wrote in message
...
"I would like to find out what problems are specific to the Hallicrafters
SX-99. Where is a good place to look? "

Inside the Hallicrafters SX-99 would be my first guess.

"
I'd be interested in which of the old caps were known to have "issues".
or to fail. Sure, they are all old (in any tube equipmnent), and they
are paper caps, which are no longer made, but I'm sure some brands were
better or worse than others. "

Some brands gained notoriety simply because there were a lot more of their
parts out there in the field.

Its probably more productive to identify suspect dielectric types than
brands.

Those were the materials they had back then, and some of them don't last
forever in the heat around tubes.