Quote Originally Posted by m_c View Post
I've been around this stuff for far longer than I'd care to admit

The main driver for how much you plan for replacement/upgrade will be how reliant you are on the machine.
If you can't really afford any down time, I'd probably look at creating a completely new control box with more modern drivers, and a suitable motion controller. The controllers already mentioned are only a couple of lots of options. More modern drivers are also likely to allow you to get a bit more performance out of the machine, but you are then heading towards the rabbit hole of how much you upgrade.
Hopefully one day I can be where you're at

It is our only machine, so we do rely fairly heavily on it. We're not so busy that any downtime is a real killer, but the prospect of machine failure is always in the back of my mind. Everything just seems so daunting!