I know the machines from that era well and can help you with an upgrade plan, as can Brady, but I'm too far to stop by.
If you send me your full specs, including motor models, pics, router/spindle etc. via email or PM I' can give you some ideas there.
Sound like you're possibly getting a com hiccup. Could be anything from a worn out cable to a driver or board issue. Like any intermittent, it can be frustrating to troubleshoot.