Losing steps/position, again

[JAZZCNC]

There is a 5v and a 24v transformer which I think are DC (I did take pictures but have left my phone in the workshop), I assume they were fitted when the machine was converted to Mach3 they are certainly not part of the original controller..

Ok if that is the case then your sorted. It would be a good idea to post picturs of inside the control box.

My spindle is controlled by a plugin and serial port which I am happy to leave as is.

If you go with the AXBB and UcCNC software then you won't be able to use it and I would use the UcCNC software over Mach3 as it's getting long in the tooth.

I would prefer to purchase a PSU as opposed to building one unless there is an advantage going the toroidal route.

Ok well in that case look for a Unregulated Linear Supply. Gary at Zapp automation used to sell 48Vdc Leadshine Unreg PSU's give him a lookup.

Regarding your comment on the 300Va being sufficient but no room for expansion could I fit bigger motors if I needed to or would I need to if the new set up get the most out f the current ones?

With 300Va then no you would need more current and 300Va limits you to about 8.5A total which could be borderline with some motors, with the current ones you probably won't have any trouble. But if one dies on you then you'll struggle to get the same size and it would be the ideal time to upgrade and 300Va would limit this.

As to using what I can I was assuming that with a new motion controller, PSU and drives apart from the 5 & 24V transformers everything else would be redundant bar the mains on/off switch.

Ermm not really you will still want some safety involved so a few relays will be needed for a hardwired latching E-stop system that safely Kills drives etc and lets the controller know there's been an emergency Stop.