You need to keep pressure in the tailstock when machining.
If not, due to small internal air leakage, the air which is in the right part of the cylinder will migrate to the left side.
As a consequence, the tailstock will move backward slowly.
I experienced the same issue on my machine when parking the tailstock to right side : after 10 minutes the tailstock was in middle position without any command!
I solved the issue by adding a gasket between the piston head and the road.
Will try to remove the gasket and use teflon tape on the thread because I am afraid of potential gasket worn when applying pressure in the piston.
But, even if you fix the leakage issue, I recommend to apply permanent pressure when machining to avoid any issue due to small remaining air leakage.
I sent mail to support so will report what they say, that is word - hammer noise
As an interim solution, you can try to configure the controller for a 2 wires encoder (pulse A + index), and not 3 wires (A+B+index).
That will be similar to the original Emco encoder.
Of course, by doing that, the controller will not be able to sense the direction of rotation (CW or CCW).
But that should not be a problem as you are not changing the spindle rotation direction during the threading operation.
It will forbid only rigid tapping.
I guess the controller will react identically in both rotation directions. and should not show the problem anymore.
one problem solved and I found new one, feedrate override does not work, yesterday was learning how to add rapid feedrate override slider on screen and went to test how it works, found out that it works , also found that feedrate overide does not work (I know 100% that it worked before), now I assume that is maybe connected with CSMIO firmware update, anyway