I would use caution prior to using a Variac, some circuits react poorly.
bimasta
I would use a Variac to coax the Denon gently back into action,
that said I'm not a teck.
"Now, next question: what's the best reasonably priced cartridge (<$1000) to use with it?"
I believe you may have read the tread on another forum regarding the metal rods that are present running down its length and were
removed by the owner to accommodate a less restrictive cartridge
selection?
Personally the only thing regarding the GT-2000 that is an "iffy" factor
for me is the limitation of optional arms that can be mounted
without some surgery.