Hi,
yeah, given the age then analogue is highly likely.

There few manufacturers of analogue capable controllers, all however in the $1000-$1500 bracket.
Given,say, a couple of Delta 750W servos and drives can be had for the same or even less than an
analogue controller...with consequent 'new' reliability and repair/replacement so much more
achievable than repairing analogue dives/servos....

Craig

Cs-labs  kanalog are about $500 and viper do an eboard to convert digital to analog in closed loop for $89 per drive