I have a Denford Micromill. I have replaced all the Denford electronics with new generic stepper drivers
like this

https://www.ebay.co.uk/itm/352981992806

and it now runs on Linuxcnc

It all used to work fine with the old Denford electronics until I fried them.

BUT now the Y axis is sticking. Sometimes it makes a grinding noise and won't move past certain points in either direction. These points vary. Other times, it moves fine. Sometimes I need to give it a helping hand (i.e. I give it a shove and then it moves). It has the feel of a mechanical problem but I cannot see anything that could be blocking the motion, and it is all lubricated. The wiring seems OK (I have swapped round the drivers and the same thing happens). I messed around with the dip switches to change the microsteps and I also gradually increased the max current. But when I went from 2.5A to 2.7A the driver blew so now I am waiting for a new one.

So in the meantime, any bright ideas?