-soldered the drive/mesa cable new
-changed the ecoder value in the drive settings to 2500 instead of 10000
-changed the values in the ini to fit 2500 instead of 10000
-set stepspace and steplen to 1500
-enabled encoder.N.counter-mode
-changed encoder direction by changing A+ and A- cables
now spindle speed form 1-8000 rpm is again possible, also rigid tapping.
Thanks for the input.
Still don't know what was the problem with the drive.