Old Precix controller replacement

I am a novice at this, I have a 23 year old Precix router and the "controller" I use that term to include everything in the black box, needs to be replaced, (it constantly loses data and I can't use it anymore). So I could really use some help please guys.
I originally planned to buy one of the kits from Ali Express but I find that the spindles on my stepper motors are 9.7mm and the NEMA 34's are at least 12mm+ . I would have bored the cogs out to take the new spindles but there isn't enough material. The mounting holes for the existing SM are the correct size for NEMA 34 motors.
I think the existing motors appear to work ok, so I wondered if I could buy just the break out board, the 3 drivers and software etc. but I'm not sure exactly what I need and there are so many choices.
Another option I might have is to make new mounting plates to take NEMA 23 motors . (I only cut and machine HDU, cedar, ply, PVC and occasionally thin aluminum sheet and the machine only runs 1-2 days per week.). I can get flexible linkages to go from 10mm-8mm. the big question is what do I need to buy in the way of controllers, drivers etc.I have to make sure everything will work together OK
I live a long way from any major city and can't afford to spend $7-800+ just on some one coming out to look at my problem. So any help at all will be very much appreciated.