Bridgeport with Herco aftermarket problems

I just bought used Variable Speed Bridgeport with an aftermarket Herco NC control and servos on it. There wasn’t any power running to it when I bought it so I don’t know if the Herco conversion works. The bottom housing of the head is cracked but I haven’t been able to find out what happened. When you try to raise the quill by the hand feed lever it goes up very hard and the lower housing starts to separate where it is cracked. It feels like the resistance may be coming from the “Z” axis servo. I think the Herco retrofit was done in the 80’s. Has anyone had a similar experience? Where can I buy the lower housing? Are parts still available for the Herco NC conversion? If I have to I’ll pull off the Herco unit and use it as a normal Bridgeport, provided that this is still an option.