Threading problem on Miyano

[Mark18969]

I have an older Miyano BNC34 lathe. It will not single point thread. This had worked in the past. At one time we lost the parameters on the machine and had to reinstall them. I do not know if this was the cause of the problem.
When we thread at a low RPM, the machine will follow the thread. Once we get to a higher RPM, after cutting 2-3 threads, it will seem to skip, and double cut the thread. We tried swapping the 2 servo drive boards with no change. We went out and replaced the spindle encoder, and that did not fix anything. That was an expensive swap. All that is left is the main board, and a possible parameter that we missed.

It's hard to get help from Miyano on this, and we are still chasing it.
Anyone out there have ideas?
Or if you have mid 1980 BNC34 and the parameters printed out, I would appreciate a copy so we can compare what we have to what you have.