We can make some assumptions here. Since your original power supply was 100V output, we can guess that the motors are 90V to 140V, most likely rated on the higher end. The 25A20 drives are rated at 40 to 190V, 20A peak, 10A continuous. Your motors are most likely in the 750W range, around 35 in/lb torque, maybe 3500 RPM max, common on that size machine. In this case torque = current, and voltage = RPM in almost a direct relationship.
What I find interesting is that your 100V, 10A power supply would not run the motors. I have a similar setup on my machine and run it with a 75V, 5A power supply with no problems at all. The original power supply was was around 100VDC and 20A as I recall.
What kind of power supply did you attempt to use? Switching power supplies do not work well in this type of application, you need an unregulated transformer type linear power supply.
I would think this one should work fine unless you really need 400 ipm rapids.
https://www.automationtechnologiesin...0vac-or-230vac
An alternative would be to use a 240/480 - 120/240, 3 KVA or so transformer. Somethinglike this one
https://www.ebay.com/itm/30415066281...oAAOSwE2FhRMzP
Wire the primary for 480V, wire the secondary for 120V, and apply 240V to the primary. This will give you 60VAC output. Then feed that to a 50A bridge rectifier and a couple of properly rated large caps, and you will have an instant 30 amp, 82VDC power supply.